Is Bigger always Better?

Over the past few releases from GW their kits have gotten bigger. Mainly in 40k with the Eldar, Tau, CSM and DA recieving some big kits.
I was wondering what everyone thinks about a powerful model being visable to every piece of Ordanance your opponent has and how the community feels.
Do we want big kits? Do we want big kits with rules as good as their price indicates? Are they powerful enough to invest in many?
So many questions... 

The Wraithknight certainly isn't a game-breaker. It's as tough as nails (it puts things into perspective when you realise even Lascannons are only stripping one of it's 6 wounds on a 3+, rock up with 3 and you'll likely have at least 2 standing by the end of the game barring poison shenanigans) but it doesn't have the offensive output to back it up, though sticking the sword on it and running it at people would probably be funny as all heck.

Always? No.

I bought my Riptide for a number of reasons. 1: It looks awesome.
2: I can't wait to get it painted.
3: It's a killing machine on the table. (heh, machine puns)
4: There's so much modelling and basing potential.
5: It looks awesome. 

I will agree that it is certainly nowhere near a game breaker, but it's pretty damn difficult to deal with. If you can get that Nova Charge off, you can turn the tide (heh, more puns) of almost every turn. Ordinance with S9 is gross, and so is 12 Rending S6 shots. On top of that, I can switch that out to get a 3+ invuln, on top of my T6 and 5 wounds. Also, you can put IC's in his unit too, which Shadowsun with all her drones chillin with a Riptide is fun, very fun. (4+ cover, hahahaha)

GW are trying to reap the rule of cool and doing what they do best, charging you a fortune for it.

It's like magic the gathering. The new sets have to come out with cards that look and are 10 times better than the old cards so you'll buy them.