I really loved the original games (through Raven Shield), but I also thought that Vegas was a really great game, though very different... overall a more dynamic feeling game. Lockdown and R6:3 were the lowpoints of the series, not Vegas. The article is off base on some things.
What amazes me most is that developers think so little of their audience that they feel they have to give them all these crutches to stand on, forgetting why people bought Rainbow Six in the first place.
I think the problem is that not enough people DID buy the earlier games BECAUSE they were so hard... I'm sure the sales of Vegas were much higher (though I'm not sure where to look for the actual data).
I miss the hardness, and I also don't... there's a lot to be said for fun. Either way, I know why they were forced to go the way they went.