Generally speaking, the cheap decks people start the game with aren't very interesting to pilot. They don't have enough removal, which is one of the primary ways players interact with their opponent's board. They definitely don't have boardwipes, which means just playing the best creature in hand each turn is usually the right play. They typically don't have much card selection. And most complexity is concentrated at higher rarities, so these decks tend to have simple cards.

That's not to say that all cheap decks are boring, or all tournament decks are interesting, but cards like, say, Duskwatch Recruiter, Dromoka's Command, or Despise, for example, just offer more choices than Craw Wurms or Grizzly Bears.

Regarding what others have said:

Damage not going on the stack was a good change IMO. Sacrificing Mogg Fanatic was always the right play; now it's less obvious. I agree with akud on detention sphere vs. O-ring.

Hexproof over Shroud was a mistake; with that said, they seem to have figured that out, and we're getting cards like Pristine Skywise or Dragonlord Ojutai instead.

I'm sad to see Protection be replaced by Indestructible. Morph/Manifest and DFCs show that they're not entirely shying away from complex mechanics.

MaRo started a "New World Order" (http://magic.wizards.com/en/articles/archive/making-magic/ne...) design approach in 2011, where they try to manage some of the complexity by making commons and uncommons have less and/or easier abilities. It sound reasonable, as casual players have a lot more commons and uncommons than rares and mythical rares, and it makes learning/enjoyment curve much less steep. Some experienced players associate NWO with "dumbing down the game".

For me, damage not going on the stack was a big change. That's probably better for the game, but eliminates a lot of tricks.

Also, the cards printed these days tend to not allow you to hose yourself. Take things like detention sphere, that say "exile a non land permanent you don't control." It used to be that those types of cards would exile any non land permanent, do a skilled opponent could, in certain situations, exile something you controlled by bouncing their only non land permanent in response.