Re: Problematic block timestamps and number of transactions?

I'm pointing to ridicule situation - there are thousands of unconfirmed transaction but block will be accepted, which means
blockchain size will be increased by 1, even though mentioned block has no transactions other than 50BTCs payout. Since
that is possible, it's possible for determined attacker to "freeze" all non-BTC-generating transactions (almost) indefinitely.

Not really. There are actually several ways to counter this if we ever need to... we can make it costly to be antisocial if we really need to.

How much worse the situation must become for that to happen? If there are already ways to fight it, why wait with implementation?

Because it's already implemented. It's the fee. It was discussed how to block antisocial blocks in the past and the result was pretty much that it isn't possible. If miners don't want the fees they are free to not include transactions. If Deepbit doesn't include transaction they are actually telling everyone that they think the fees are too low and there's nothing wrong about that.