I remember back in 3.1 or 3.2ish, a lot of buzz was going about the WoW healing forums about paladins and how gemming intellect isn't "fun".
I was always a little confused about that (is gemming something else more fun?), even if I myself do enjoy watching my mana pool go up with each new socket. Several tiers ago, I didn't think there was really any fun in gemming or enchanting. You merely pick the best gem and forget about it. Same with enchanting - I've been using the same enchants on upgrades this expansion, and it's usually a no-brainer because if you're a caster, there is no choice many of your enchants (for cloaks there's really only haste, and for legs and gloves there's really only spellpower). My paladin has been ignoring socket bonuses all expansion long. I keep yellow gems on hand for those new upgrades since there's no surprise what I will want to socket when I get them. I don't think this is a bad thing, this is just life for my paladin who specializes in tank healing.
I ran ToC10 with my druid today. She's got some pretty nice gear, and she's getting more (if only I could make myself run a few more randoms every day...). I had a blast in ToC, even if the paladin healer was from a notoriously bad guild and I spent more time taking care of the tanks than he did. It's cool, I do prefer getting my badges and loot than wiping to prove someone is bad. Anyways, I recently got Merlin's Robe crafted, and today I got Enlightenment. Lots of gem sockets, hurray!
I have to say, I had fun gemming my new gear for my druid. It's because she has so many choices and druids enjoy the benefits of a balance of stats, more so than paladins. I happily match socket bonuses for her, and use hybrid gems to give her snippets of spellpower, haste, spirit, and whatever else I'm feeling up for. I feel there's less wrong ways to gem my druid, and that's fun to me. I intentionally don't stack on her, because I do on my paladin. I like the contrast of the two gearing styles, and I enjoy my paladin more now that I've raided on my priest and druid. Each has its weaknesses and it's strengths, and I appreciate those strengths more when I see I play the characters without them (I am so very glad my paladin can cleanse magic debuffs, even if she can't run in circles casting instants like a tree).
While I don't consider stacking Intellect "fun" in and of itself, it enables me to have a lot of fun in the raid because of how much more casting I can do, and how much further it puts me away from going OOM. Out of all of the things in this game, I can definitely say that no mana really does equate to no fun. If that what it takes to make stacking Intellect "fun", then it's mighty fun indeed!