Technically, it was about the PS3, albeit running PS1 games ;)
In PS1 times, very few people here had SCART. You may have been different up there in Staffordshire, but down here in Kent, it was a rarity. Fact.
In the present, yes it's usually built into a television and so won't cost the consumer any more, assuming they have such a television. Your argument would have been better served from a manufacturer's point of view, though. It's not expensive to implement it in a television, but it's more expensive to replace a non-SCART television with a SCART equipped one.
Getting a Sony PVM or a Commodore Amiga monitor is a good way to go for retro gaming in the US, getting back on topic. They can be picked up relatively cheaply nowadays, as people don't really want them (I even saw someone giving away a Philips CM8833 on a forum recently - in the UK, but still).
I'd never get a plasma - LCDs are great nowadays. Samsung make some stunning LED televisions. Yes, having a dedicated RGB CRT is nice for classic gaming, though.