1. Spellmaking was broken.
Spellmaking had flaws that needed fixed. Instead of fixing them, they made an entirely new system, and guess what? It also has flaws that need fixed.
2. Characters who exclusively focus on something are weak. A character taking only 2h talents (but no blacksmithing, no alchemy, no enchanting, no block etc) is gonna have your same problems. Spend some in Conjuration. Skill up enchanting and boost your magic through your gear. You'll get awesome results.
You're telling them they can't do something that the lore itself supports, that all prior games have supported on a mechanics level. Concentrating in once school of magic has been a part of TES lore and gameplay for as long as it has been around (though you didn't have to, you could study multiples). Even the NPC mages in Skyrim specialize.
It's only the player that can't specialize in certain schools very well. Conjuration is extremely good, I'm enjoying, I could easily concentrate on just Conjuration and be successful as a Mage - bound weapons and summons are superb. However, I don't, I choose to concentrate on Conjuration, Destruction, Illusion, Restoration and Alteration. The fact that I like doing this, the fact that I enjoy having so much access to multiple schools that means nothing. I enjoy it. It doesn't mean everyone does. Especially given lore, past games, and even current NPCs have all supported specialization.
Certain schools like Restoration, however, simply don't support it anymore. Those players that used to be able to get by on Restoration or another school that's been changed (or removed entirely) have every right to be disappointed. They have every right to take issue with it. They have every right to complain.
Hopefully once the Construction Set comes out, and a few mods are made, those people will be able to get back to what they enjoy. That is what's important. What they enjoy.