I think you guys are overstating the power of fire decks. You're playing against AI's and not people plus once the true PvP comes out we'll be able to see what really is most effective. Fire doesn't need to have firebolt or fahrenheit capped at this time because in reality its a slower deck that can very well be vulnerable to faster decks and aether decks. Anyways if fire was such an effective strategy at this point you would see many more people in the top 50 running it. Thats not the case and in fact I've been playing against a variety of decks since nova's been weakened.

In regards to your aether being overbalanced if you were to do what you mentioned to the dimensional shields you would effectively ruin(or nerf as some call it) the all aether strategy because its cards are so expensive in the first place. You need to be able to stall with the dimensional shields in order to have enough time to get all the quanta needed to summon a dragon and use parallel universe a couple of times. Aether is a slower strategy so you have to be able to slow down your opponent somehow plus the price of the dimensional sield has been raised as well. I personally have 17 pillars in my deck to make sure I can get enough pillars in the beginning(I'm sure you can guess the rest of my cards yourself :P).

As for a smaller card limit I'd be in support of it because it would provide more variety to the game because players wouldn't be able to focus on a single strategy as much. They'd have to be able to go in several different directions. Another idea might be to bring the minimum deck number up to 40 so that people would have to have a larger deck and maybe even duel type their deck so that they can have the variety to fill the 40 cards up. Maybe even both could be put to use. In an old card game called Yugioh I used to play the card minimum was 40 and you could only have up to three copies of a card in your deck and even less for the cards that were more powerful(granted there were a lot more cards in that game than this one.) Putting either of these two rules in effect would make players have to branch out in their strategies and further differentiate startegies within the game.