Although I don't really play Pop-Caps games, I love that they exist. I can't tell you how pleased I was to go to lunch with my wife and a bunch of her friends (mostly 20 something, married women and their husbands) and see them all chatting about playing Bejeweled and watching the "Zombie No More" song from Plants vs. Zombies over and over again. It might not be hard-core gaming for the masses, but it is gaming: that's a very good thing.
I'd say Bejeweled has much more to do with the modern match-three puzzle games then Columns. I've played a lot of both and Columns is still trying to hard to be Tetris with a twist. The main thing being the full play board of Gems that games like Bejeweled and Puzzle Quest have. This really changes the game play from Columns falling gems. The experience ends up being very different.
Columns is still a good game but I find it not to be the most enthralling experience.
Casual gaming is really damned by the hardcore gamers nowadays, but gaming really needs the 'find a mechanic that sticks then work it to the bone' mentality Popcap so obviously has. Not saying that I don't like the 'everything and the kitchen sink' approach most mainstream games have, throwing a bunch of mechanics and letting you do whatever, but... well, that's like comparing Airplane! to Psycho. I love Airplane!, it's very fun and always a nice watch, but it's not even in the same level as Psycho. Psycho is actually probing the medium of films deeper, it's setting a bedrock.
Not saying that Bejeweled is setting a bedrock while GTAIV isn't, (though that might be true), but the mentality that advances gaming as a medium comes from that. Gameplay is the language of games.
I love PopCap. They just have the basics down so well - no tutorials, no NPC's, just the basic gameplay mechanic distilled into simple, enthralling games. I've got the most hours on Steam logged into Tropico 3 - a complex RTS game. But next comes Plants Vs Zombies and Bejeweled. I just keep coming back to them!
"Bejeweled also birthed the match-three puzzle game genre."
Uhh, no. It had been around for years before, Bejeweled was just the latest incarnation. I'm sure that's why everyone's able to clone it without PopCap stopping them -- prior art and all that. Just like Zuma, it's a derivative of earlier arcade games.
I think that one of the bigger things driving Popcap is not only their ability to take a complex genre and compress it down to a simple design, accessible to the more casual audience, but to take that design and coat on subtle layers of depth that will keep a more hardcore gamer invested. I'll still hop onto PvZ on occasion, going, "What if this combination of plants in this level..."