Good from what perspective?
From the PC gamer’s perspective? Of course! From console gamers’ perspectives? Probably good for them too, especially because a lot of them could play the pre-Xbone games on their computer instead of dragging around an old 360 to play the old titles (I really doubt the Xbone has the power to run a 360 emu). From M$'s perspective? Yeah, probably good for them too. I’m sure they’re making basically zero off 3 and Reach by now, so porting those ones and earlier would be nothing but easy cash.
Do I think M$ will actually port the earlier Halo’s to PC? Probably not. Spartan Assault is a good sign and all, but I really don’t see it happening just because M$ has been rabidly pushing the Xbox division at the loss of PC gaming for over a decade now. Maybe the Xbone’s weak showing will encourage them to return to the PC market, but I wouldn’t expect it.
After Halo 2 I think they really saw the PC market as dead to piracy, when really the reason Halo 2 was such a flop was because it was artificially restricted to Vista (some of the pirated versions came with xp support cracked in). I really can’t see them not restricting PC Halo titles to the latest OS, and unless Windows 9 adoption is through the roof that’d probably just backfire again. I lost all hope when CE Anniversary never got a PC port. That was a HUGE slap to the face of PC gamers and I think really made their disinterest in the PC gaming market clear.
I personally consider M$ to be one of the most poorly managed large corporations in the entire gaming market, hell, in the entire tech industry. Nearly every single thing they do is an easily avoidable blunder that makes it painfully obvious that they’re not in touch with their consumer base. Not to mention they have a history of aggressively pushing failing products as opposed to fixing/dropping them (Kinect, Vista, to a lesser extent Win8…).