It's not really worth it for them to make dumb TVs either, I assume, since that implies they can't shove ads and telemetry into them.
Making a firmware that does "nothing" is probably less work than making one that does a lot of things. So even in the new currency (developer time) it might be cheap and make some people happy.
Which is GPs point. Open source TV firmware means that the manufacturers motives are no longer the totality of the conversation.