well higher connectivity alone is a good thing.
Sure, but that's irrelevant to the discussion at hand.
to still keep an incentive for smaller blocks we could implement that not all of the rewarddiff is distributed to nodes; just half of it (and the rest is lost)
That goes waaay further than changing a constant in the code. Don't get me wrong, if it didn't completely fuck up the incentives the max block size constraint would already be long gone, because it would be a no-brainer. The problem is that Bitcoin has a cost, and that people expect it to be paid forever by inflation, like it is today, except this doesn't work.