First of all, we all know that having BTC address in your profile doesn't work as a tipping tool. It's not convenient, but mostly, if you tip someone, you want them to know that it was you and you want them to know which post you tipped them for. Tx fees also don't help.
Integrated tipping would be a great addition, but I do understand why theymos wouldn't want it. It would be a massive pain to maintain cold/hot wallets and he would take a big responsibility on keeping funds on behalf of thousands of members. KYC/AML shouldn't be an issue as appropriate limits could be set.
Changetip is not as functional as tip button, but much more feasible to implement.
If anyone's curious about how tip button could look like, here's the example from Polish forum (bitcoin.pl)
In the right top corner (circled) you see tip option with 3 pre-set amounts (0.0001, 0.0005 and 0.001), you can tip the post multiple times so if you want to tip 0.01 just click 0.001 ten times (not very convenient but works). Those 3 fields are grey if you don't have sufficient funds in your account, when you do - the colour changes to orange. If you only have 0.0001, then the smallest button is orange, other 2 are grey.
On the left (circled) you see "tips for this post", you can click on it and see who tipped and how much.