But if this -for example- uses more CPU% (or bus-timing), there could be devices having trouble with it.
But why assume such things? And in the remote case where it is, why decide for others which is more import for them? Give them the choice and let them make it themselves.
Why not try it yourself and inform OpenWrt development about the results?
Because I'm not really kitted out do to source builds and it's not a trivial process to get there. I use the imagebuilder to build my firmwares. It would be orders of magnitude less effort for one of the main developers to make a single line switch change than it would take for me to get kitted up to do source builds.