The 3e bard also has strong magic--it's rather artificial to say that they only get spells up to 6th level then say that a powerful spell is 8th level for wizard but 6th level for bards. We won't know whether their magic is too much or not enough until we see the full spell list. The key to balance here is not the number of spell slots/levels, but the scope of their abilities. Wizards are powerful because they have spells to do almost anything except healing. If bards get 9th level spells but only enchantment/illusion/support magic, then their magic is unarguably weaker.
Yes, with full spellcasting for the bard, there should not really be a need for spells to be available at different levels for different classes: a spell of 5th level stays that way all the time. Makes the scaling by increasing a spell slot a lot simpler.
Also here is my explanation from the wizards board, why I believe, the bard (and also the cleric) are not full casters:
"I believe it is the right idea to give the bard better spellcasting than the paladin or ranger. And in the last hours i thought about 1/3 spellcasters and 2/3 spellcasters. And then I cam to the conclusion: we already have 1/3 and 2/3 spellcasters, despite only having full and half progression. And here is the reasoning why:
The wizard and druid currently are only two classes I count as full spellcasters. They have a mechanic to recover some spells. At level 20 they can recover 10 levels of spells, which is quite impressive, when you know that half casters only have 30 levels of spells at level 20. (2 of each from level 1 to level 5 spells). Wizards get eve more spells with their schools of specialization.
I guess the sorcerer will be on par with him by the means of his sorcery points.
The cleric and now the bard will be 2/3 spellcasters. Full progression, but most probably no means of extra spell recoveries. They can make up for this with their fighting and/or skill prowess. A battle cleric currently does very well in combat. I believe the bard will be about on par with the cleric in that regard if they chose the right college.
The paladin and ranger are 1/3 spellcasters. Only levels 1-5. No means of recovery. They are warrior type classes with full fighting prowess.
The barbarian, fighter, monk and rogues lack spellcasting but get their unique mechanics. I hope they won´t suck.
In the end, after thinking it through a bit, I like the way the bard is heading, and really hope, somewhere beween barbarian and bard is a space for the skald, and somewhere between the fighter and bard lies the warlord, and somewhere between wizard and bard lies the loremaster.
overall
edit: concept wise, I see the bard as redmage from now on. Mediocre at everything, but buffing and debuffing, where he is the best. Still makes him a good solo character, but truly makes him the most wanted 5th man."