"Relative to the number of users" huh?... and why would that be a relevant metric for anybody?
Because if namecoin was widely used the cost of running a full node would increase. It has _far_ less usage than bitcoin and already it's about 18% of the blockchain size. Namecoin's design, unfortunately, doesn't enable lite resolvers (there can be no equivalent of a SPV node, like bitcoinj, for namecoin with its current design) of any kind which I think will probably doom its adoption. I posted a sketch of a design to solve this last year, but other than the addition of merged mining namecoin development appears to be more or less completely dead.
I consider this to be fatal flaw which will ultimately prevent the adoption of namecoin unless it is resolved.
To the end user, using namecoin to ensure a secure connection to a full bitcoin node is way cheaper than running a full bitcoin node ... or are you disputing that point?
That makes no sense at all and doesn't follow from the technology. Namecoin is fundamentally more computationally costly to maintain because you _must_ have multiple unspent outputs pending in order to have multiple registered names (whereas any amount of bitcoin can be represented by a single txout), and you must carry additional indexes on them in order to perform lookups. (bitcoin txn only require lookups by txid).
These aren't any terrible flaws, but they're reasons why a full namecoin node— if as widely adopted as bitcoin— shouldn't be expected to be less expensive to run.
A fully validating bitcoin node can actually be operated with less than 100 mbytes storage, though the code for this is not mainline yet.
Obviously namecoin doesn't have as many users as the proportion of the hash power it commands, this is precisely the piggy-backing onto the bitcoin hashpower merged-mining allows ... this is the second time you have thrown up an irrelevant arguments without pointing out exactly where the problem is you are complaining about. Third strike and I'll assume you are just trolling.
Can someone please decode this for me— because I don't have an idea what you're talking about. I can assure you that I'm not trolling.
To the contrary, you've still made no suggestion about how namecoin could do anything to address the fundamentally hard problem of this thread: Demonstrating the independence of weakly trusted central servers, as required for the exponential security model given in the OP to hold.