Smithing is flawed because:
1.) How you gain experience is not contingent on the quality of item. The better the item, the more experience. At a certain point, crafting trivial items should yield a highly degraded skill increase. Players should have to use higher quality materials to raise their Smithing skill.
2.) The Perks for Smithing are silly. The effect of the Perks are HUGE. They can quite easily scale out of control and the fact as soon as I get say Ebony Perk, everything before that becomes obsolete and just pre-reqs. I believe Perk point investments should provide continual benefits. I think it is asinine that basically, the only reason why the Smithing tree is as screwed up as it is is so the "immersion" seekers can take Steel Armor and improve it to the cap and do not have to trade off armor values for RP visuals.
3.) The way the Perk tree is constructed is crazy. Light Armor has 1 less Perk point tier and the Glass Weapons are not on par with Daedric. The best Light Armor is Dragonscale which you can get from the Heavy side, yet Dragonplate is NOT the best Heavy armor. This means you are better off Light or Heavy going the Heavy route as the best Weapons and Armor are that route.
4.) Buying raw materials are incredibly easy to do. You can craft everything MUCH quicker than you can find it. This leaves players who invest in Smithing unenthusiastic when the gear they find is worse than what they are wearing.
5.) Smithing is the only way to have your gear scale. There are EXTREMELY limited tiers of weapons and armor. Considering Base Values are static, a player MUST invest in Smithing to raise their damage output.
6.) The Concept of Smithing is bad. Typically we refer to crafting as a "tradeskill". The reason being as it is used as a source of income for players to TRADE with other players. Typically, the reason why you had to trade was because you could only invest in a LIMITED amount of professions, and some recipes required materials from OTHER Tradeskills. This fosters an economy. Skyrim, is a Single Player game. You do NOT need tradeskills in a Single Player game, and actually you are BETTER served having that reside with NPCs.
7.) Not enough customization. What you do with Smithing is not unique to the game world. You make the same bland items that can be found in the game. Materials are easy to come by and once you make one piece for you, there is no need to make another, outside of how crappy the Enchanting system is you cannot overwrite Enchants so as you level Enchanting you will need more sets of armor or weapons to place higher and higher Enchants on.