Mechanically, it is a lot harder to reach the sweet spot with aspected mages. For full mages, Priority: A gives you a Magic of 6 as well as bonus skills and spells. For adepts, Priority: B gives you a Magic of 6 and a bonus skill. For aspected mages, well, Priority: B gives you, well, a Magic of 5 and a rating: 4 magical skill group. So you need skills: C or better to get that skill group up to 6, and 7 points of your starting Karma per skill if you want any specializations. Also, unless you are playing a human, you will need metatype: C or better to be able to start with a Magic of 6. And finally, sorcerers have to buy spells with starting Karma - a sorcerer who takes no positive qualities, 25 points' worth of negative qualities, and spends all 50 Karma on spells will have the same number of spells that a Priority: A mage gets for free.
Plus, sorcery and conjuring are both incredibly useful - and complementary. Spirits can aid spellcasting, sustain spells for you, and even cast spells for you (but the innate spell power has to be a spell the summoner knows, so suck it, conjurers). Spells can often fight or protect against hostile spirits better than the banishing skill can. Frankly, even under the much fairer Point Build rules, the opportunity cost of getting the complete magical package is such that the only real reason for playing an aspected mage is if you have an overriding roleplaying reason for it.