This is small, the biggest bug in BU has still not been fixed and is not even recognised as such.
i.e. Emergent consensus failure bug
The 'emergent consensus' mechanism means miners can increase profit by increasing the blocksize.
The only thing stoping increasing the blocksize is the increasing cost of bigger blocks due to orphan rate.
To optimise for profit miners will have competitive pressure to reduce orphan rate and that is easily done by centralisation of mining.
With centralised mining Bitcoin is led to a permanent failure mode as it devolves into a fully centralised system. Centralised mining and centralised nodes.
This is a massive, massive, catastrophic bug that would slowly kill Bitcoin if the network would run on BU (unlikely). This still has not been fixed by Bitcoin Unlimited.
Can you explain how miners increase profit by increasing the block size, this doesn't compute for me. Currently miners are gaining the most out of everyone from the current status quo because of the rising fees. They could be thinking long term ie lets not make $1 on 100 transactions, let's make $0.001 on a Million transactions, but that's a long long way off and might not ever happen.
Orphans with bigger blocks would be a problem sure, which is why from what I have read, any increase that comes about will be done slowly and incrementally, again they have the most to lose if they move too quick and get orphans.
The days when everyone could mine in a significant way have long since passed, and we just have to accept the reality of what has happened, mining is now fairly centralised amongst a number of very large private farms, I don't like it much either, but it's a done deal and I don't see any way that 'bitcoin' can change that now.
Centralised nodes is just a red herring, even if blocks jumped to 32Mb tomorrow which is not what will happen, most nodes would cope just fine, and for those that can't maybe pi users with small cards then prune is available already. Although I run 2 nodes (one of each btw) I'm not convinced that they are that important anymore and most people don't need the full blockchain anyway.