Sonos amp lack of trueplay

I am not sure if you are alone, but I would guess a tiny minority. You would almost certainly get a far greater improvement in sound quality by spending the money on better speakers. 

I don't doubt that, but the amp is capable of room correction and I don't get why that feature is locked. I can't even tweak the sub because I don't want sonance speakers.

Sonos reason for not allowing room correction also is weak. Their reason is that they have to know the response of the speakers.

I mean Direc have solved the problem of room correction no matter the combination of amp and speakers in use

One should always consider another manufacturer if one is dissatisfied with their current setup.  Unless one is just blustering to get the current manufacturer to change their ways, because that is probably not going to be successful. 

It would just be so much easier to have room correction enabled instead of changing the system.

But it looks like a system change is the outcome 

Of course it is doable.    But Sonos has to ask whether the increase in revenue would be greater than the cost of development and implementation.  And even if it were, is it a better use of scarce development resource than other potentially profitable developments?

Maybe Bluesound operate in a rather different target market.  Maybe Sonos will introduce this in a future iteration of the Amp (it will need a microphone, I would guess).  I honestly don’t know. It’s your right to take your business to whichever company meets your needs best overall.  But just because Bluesound has done it, it doesn’t make it sensible for Sonos to do likewise.