Skyrim allows you to eliminate magicka depletion for two spell types by enchanting four items with the reduce magicka cost enchantment. I'm trying to decide whether if it's cheating or not. What do you think?

no, it is using regular game mechanics to do it, so no, it is not cheating. Cheap? maybe, depends on your view, but no, it is not cheating unless you have some deformed, warped view of cheating.

I decide all matters like this by roleplaying. If an action is appropriate for the character I'm playing then I do it. If it is not appropriate for the character I'm playing then I don't do it.

IMO it cheapens the game, but I wouldn't consider it cheating. It's something that can be achieved through normal means without exploiting any bugs.

It's not cheating in my book, and it probably makes a pure mage build much more manageable.

Usually the people that do this kind of thing are the same ones complaining that Skyrim isn't fun. Don't go overboard with it.

Since it is possible to get free casting (Conjuration is the easiest Skill to get free casting in) using the Vanila Game, I do not think it is cheating.

I have found from Personal Experience it can make the Game boring if abused. Destruction requires Cost Reduction through Gear and Alchemy to be viable at higher difficulties when used as a Mages main offensive Skill.