D&D is absolutely tuned more towards M;TG. I mean, magic was a huge, huge, huge, huge success for Wizards. It was a capital-p Phenomena. Of course they'd try to figure out why it was such a smach-hit success, and try to spread that special sauce (once identified) to it's other big brand: D&D.
I think what WotC observed was people spending hours catagorizing and building decks. Coming up with new combos. I mean, Magic is won or lost during deck construction--the actual game play is almost entirely incidental.
People spent much more time thinking about Magic, collecting Magic, discussing Magic, and building decks for Magic than they did actually *playing* Magic.
So WotC tried to add Magic to D&D. The class/feat/spell system begs to be optimized. With d20, players can spend hours thinking about, talking about, and tweaking character combos. This is Good for WotC because, as before, people spend very little time actually playing D&D (typical group meets 1 or 2 times a month for 4-6 hours). By adding Magic to D&D fans can spend time tweaking characters, which means they're thinking about D&D, which means they're more likely to remain fans/purchase future products.
I think it's a Good Thing. I'm one of those people that, when presented with a rule set for a game, automatically starts looking for patterns and exploits. I'm the guy who always takes the center square in tic-tac-toe because it creates the most possibilities for a win. The guy whose Dwarf used a longsword in OD&D instead of a dagger because a longsword does more damage. So the whole feat/class/spell possibilities in d20 are a real joy.
I imagine 4E will skew even farther toward combos, and I'm all for it--as long as they continue to put a big emphasis on balance. That's one of the terrific lessons of M:TG. Tons of new abilities and combos are good for the game only so long as no single ability or combo overpowers the others (and thus reduces the number of options to 1).
Long post, so to summarize: D&D + M:TG = good*.
-z
* As long as it doesn't descend into "collectability."