At the moment, I think we have an abundance of API nodes, relative to traffic levels. So I think there's enough incentivization now for at least top witnesses to run API nodes. Not all of them do, but again, it's not really needed for all of them to do so now, and they can always make contributions in other ways.

Now the above paragraph is mostly about "now". It's hard to say how things may look in the future, and we may be able to decentralize the infrastructure on a much more massive scale in the future, in a way that would make it less difficult to operate a node in the system, and so that we place less reliance on individual nodes. I think a sort of ideal state would be where the entire system decentralizes down to the level of individual users who all collectively support the infrastructure, and I think it's achievable in the long run.

I don't think it makes sense to change the reward curve for block producers right now, mostly because the witnesses act as elected representatives for consensus changes, and it gets too difficult for voters to track the motivations and opinions of these representatives when too many witnesses are involved in this process.

That, in and of itself, doesn't necessarily mean that we couldn't change reward curve (as was done once before), but leave the relative number of blocks produced among the top 20 witnesses the same (the relative amount of blocks produced is really important, because that's what drives the forking logic in the case of consensus disagreements). And in that case, it wouldn't even likely change the number of missed blocks, unless we assume that top witnesses would simply stop caring about missed blocks because the financial penalties for missing a block was just so small.

But as far as I can tell, there's no major issue here right now, so with many tasks to take on in the development of Hive, I think we can probably class this one in the category of "if it ain't broke, don't fix it".