But it does change the "core principles of Bitcoin" like decentralization of mining nodes.

Yes, but it is not the storage that we are concerned of.

It's the bandwidth and the computing power - keeping only the UTXO does not change much here.

I think everyone who is shouting today that we should just increase blocks size, or even allow micro transactions, should commit himself to run a full bitcoin node continuously, for the next 10 years, paying all the costs of it by himself.

Maybe then he would have understood

It's very simple. If it has the same ID, then it must have everything else also the same - pk_script(s), the value(s)...  whatever
So it doesn't matter which one of the two gets into an actual input while being spent, since they are both identical.

You have an index of unspent outputs, where each key consists of 36 bytes (TXID+Vout).
Now when you have a database that allows you to have duplicate indexes - then you just don't need to do anything. When you see the same TXID being mined, you just append it to the table. When you spend it, just make sure to delete only one record from it.

But if one day you switch to a database engine that enforces you to use a unique indexes - then you have a problem. Not a big one, you can work around it by adding a count filed to the unspent record, but nobody bothered.
It's OK that nobody bothered, it wasn't worth it, but my point is that blaming your (a developer's) problem on "broken miners" is just not fair, since they were not broken, but 100% protocol compliant at that time.

So yeah, since you used this word already, IMO you did steal that coins, and that is why when this, as you call him, "broken miner" would realize it one day, he should be entitled to a refund

Are you sure?
My understanding was that the previous Berkeley DB could handle no-unique keys and up to that moment all those transactions were spendable.
Moreover it was a well known fact that coinbase transactions could have the same ID and it was just openly allowed by the protocol, though not used too often. I believe there was even an explicit comment in the source code saying that same TXID is allowed for coinbase transactions.
So that could had been a design or implementation flaw, but it definitely was not considered as a "broken miner", neither "the same coins twice" - at least like two years ago, but I understand that history books can adopt quickly to a new reality

After switching to LevelDB the same keys (representing TXID) just merged into each other, became undistinguished in the DB, and only since that very moment coinbase with same ID have not been spendable anymore.
But before, with Berkeley DB you could spend them, as many times as they had been mined - at least that was my understanding, so please correct me if I'm wrong.

I think it's more likely that the community would let a fork go, rather than trying to beat governments on hashing power, resources, or (lack of) anonymity in order to run a node, or a miner...

People can adopt easily and they can easily switch to another branch, if they find an actual need to do so.
In fact, knowing life, I wish they didn't, but they probably will.
But I don't think it will be the end of the world.
If we managed to gather so much power to build this net, we can as well manage to move this money into the right branch, after a potential fork.
When the chain splits, the hashing power must also split - so the risk of a 50+% attack gets actually lower for you, because you get to choose to go with a branch that you personally consider less vulnerable.

I dont know. Maybe something like: https://en.bitcoin.it/wiki/BIP_0034
I think it happened in the code, when they switched to LevelDB.

It doesn't matter - whoever had that coins didn't bother to spend them on time, or more likely, nobody had them anyway.
And besides, he can always go to Gavin for a refund

No.
It's in AcceptBlock function, in main.cpp

At block #239314 there are 6187163 unspent outputs (plus 2 that had been abandoned because of non-unique TXID)

There is an RPC command in the official client that can print it, after awhile.
I don't remember the exact word, but I'm almost sure that is starts with "get" and does not take any parameters - see "help" and you should find it easily.

Except from the ones who don't know what RAID array and >1Mbps network connection is.

It just has to run on any PC than can play youtube - then I'm fine with it.
If a PC plays youtube, but cannot keep up with the chain - then the chain is broken.

sometimes I get these feelings like all the people know what they are talking about, except me.

I, at the other hand, think that this is the most important thing that we should actually worry about

well it's sort of rude to talk about what he means while he's reading it, so can answer himself.
but I started - I know, sorry

I think he means we should stay together and join our power to protect the net

Sounds like a word of a wise man

It's actually quite interesting topic to consider.
Splitting the coinbase into forks, where one stays at the limit, while the other one goes unlimited in size, or there are more branches, with different limits...

I think technically that could be done quite easily. Almost naturally - you just let a fork go and see how the market acts upon it.
BTC would split into BTC1 and BTC2 and from that moment each of them would have a different exchange rate. At the beginning, probably both below the last common price, but later - obviously either of them is still better than any other concurrency..
Maybe that could actually work

OK, so now I see some bitcoin war having a chance to pop up in a near future. People vs corporations?
It's not good, and I surely hope to stand on the right side.
Though, I don't think it's likely for me to move to the enemy camp, unless they just force me. But I will surely try to fight, FWIW, because I want to have a bitcoin node in my home 10 years from now. I mean, without a need to have also an A/C to cool it

Exactly.
So my idea is: leave the limit as is, and let the fee market to work. This will naturally create incentives for payment processors to appear and compete with each other. Just like mining pools do ATM. It even makes a lot of sense that the mining pools would become payment processors.

It's not a lie, man.
1 MB block limit - it's there and has been there for years, whether you like it or not.
Was it Satoshi himself who added it - who cares? Who is Satoshi, anyway?
The only thing that matters is that some people don't want it to grow bigger, and they have an actual valid reasons. Very important reasons.
And you accusing me of "making up facts" - it's just silly

I don't like the way you're talking to me, but out of the respect for other people reading this thread, I'm not going to reply on your void accusations.
But you are wrong - all the way.