I think that system can be confusing to new players who would splash into 4 classes without realizing that their abilities can't decently support that many different classes simultaneously.
Also I've always felt your initial class to be a part of your backstory along with allocatable ability points - those all represent your level of training and preparation. Starting with 8 intelligence as a fighter and immediately branching into a wizard would completely devalue the lore behind the wizard's training.
Forget about the lore, the lore would be the absolute last of your problems if you had a wizard with intelligence of 8...that would be outright broken and useless. it would be a purely wasted level. A wizard with intelligence of 8 just does not work.
