I don't have 4 skills maxed out nor do I plan to max 4 skills, I plan on maxing 2 skills and the rest will be incidental I was merely responding to the reply that said people would want to max pickpocketing and lockpicking. My reply was to merely show even if I maxed those (which I don't plan to do) I won't be over level 40.
The problem starts to creep in before level 40. Even at 35 with FREE destruction spells, the fights with the slightly beefier enemies drags on forever. And this is dual cast spamming thunderbolt. If you didn't have free spells, you'd be S.O.L. One of the BIGGEST problems at the moment is how plain inefficient destruction spells are in relation to how much damage they do.
I know you haven't experienced this, and probably won't, but there is a point where continuing to level MAKES YOU WEAKER as a mage. This is.....just absurd. I know that you'll probably say something to the effect of, "Well you don't need to level that high" or, "But you are not just using destruction then" but realize how foolish, FOOLISH it sounds that you would get weaker from leveling up. This goes against all common sense.
Here's a fun example, if you've ever played Pokemon. Do you know the moves sonic boom and dragon rage? They are very similar, except that dragon rage has double the damage of sonic boom, one does 20 damage, the other does 40. At the beginning of the game, where you are most likely to encounter these abilities, they are...fairly respectable, if only because they do a set amount of damage and ignore weaknesses and resistances. But at the middle or end of the game, you'll never use them. EVER. There are far more damaging moves you could learn. Even if you could spam them endlessly, they would be worthless, as your opponent would have killed you with much stronger moves. Firebolt and incinerate are good anologs to sonic boom and dragon rage. They do very well at first, but they are very impractical later when you take into account abilities that scale with other attributes.