If Mysads dominate so much, then yes the rules as they are are partly to blame but then so are the GM's because the GM's have been handed extra tools to counter characters that rely too much on sustained spells and spirits, background Count and enemy dispelling are just two of them, but probably the two most effective in this situation. Physads and mundanes on the other hand operate more or less like normal in these situations.
The thing is, this balance issue that so many talk about is partly our fault as well for not using the games balancing tools enough then. Seriously an eveil minded GM could make it practically impossible to play a mage or mysad if he/she so desired by using nothing more than the games balancing tools. Of course such a game would hardly be fun in the long run, but it does illustrate that the Whole issue about balancing is more than a rule question, it is also a gaming style question.
As i said in an earlier post, it is an illusion to think a game like this can be totally balanced right from chargen, magic does tend to screw with game balance and its like that in every game i've ever played, but shadowrun actually gives us more tools to balance characters during gameplay than any other game i've played especially magic characters.
Oh and Adzling is correct, this thread has become somewhat derailed.