now would pools jump to 2mb where there might be hit by that bug AND say 5 other propagation issues aswell all in one swoop of mega F*ck-ups and then have to tear up and remake a 1mb block with half as many tx's to try again..
or wrongly guess that it must be an issue at 2mb so try 1.9mb and have that block too throwing a tantrum in the orphanage, then try 1.8 and so on all creating orphan tantrums trying to find a new 'sweetspot' that is acceptable(to potential knitpicker: yes i know bitcoin doesnt have an actual 'orphanage' place, im just entertaining wordplay of 'orphan drama' to entertain the imaginations of people with short attention span)
Are you saying that the network participants should put *trust* into the miners in hopes that they don't centralize in order to reduce orphans, but rather produce smaller blocks?

what are you even on about "centralize"
the pools earn more by competing.
1. jumping to 2mb instantly makes propagation delays and loses the competitive advantage. so pools will move in small increments to keep their competitive advantage
2. no point jumping to 2mb because there may be several bugs and if going to 2mb then down hoping to find a sweet spot can cost them multiple blocks of wasted time.. can cause many orphans.. due to bugs and propagation.
3. going up from 1mb in small amounts reduces orphan risks and keeps a good grasp of acceptable propagation times.
oh and if you think that going from 1mb to 2mb in small increments of 250bytes would take years.. and thats your real argument im betting.
your wrong. it can take a month of safe testing the water with least orphan risks and least cost to pools and their competitive edge.
increments of 1kb can get to 2mb in a week and increments of 0.25mb can get to 2mb in under an hour
so relax. its best to be safe.. rather then have been waiting years just to get a chance and then try to rush things in 1 block or 1 hour.
1 extra month of good practice safe increments isnt gonna kill bitcoin. but jumping straight to 2mb could cause another 2013 event.
pools are smart enough to know this