I like the Steve Morse version of Purple quite a bit, actually, and Jon Lord was unmotivated during his last several years in the band. Don Airey has really come in and jump-started things, and he's pretty much the only other guy who has the right skill set and history for that gig.
Dave, for that matter, have you listened to the last couple of records that Ritchie made with Purple or any live audio from that period? "Suck" is not a sufficiently strong descriptor.
It's actually kind of a funny story around that. The rest of the band had gotten so cowed and demoralized by Ritchie's shitty attitude and poor work ethic that they booked a big bunch of rehearsal time after he left and they recruited Satriani for the '93 Japanese tour. They thought it would be really difficult to make it work with Joe. Satriani came in having learned the set off a board tape they sent him, and they pretty much nailed the entire set on the first run-through. They used the remaining time to add in some new songs that Ritchie had always refused to play, like "Pictures of Home" and "Maybe I'm A Leo."
I have audio from Satriani's time that absolutely smokes anything they did with Ritchie during the reunion era (1985-93). Morse had a little more difficult time fitting in, but he was able after awhile to put his own stamp on the band, and they've really been reinvigorated in the last decade or so. The most recent studio album, Rapture of the Deep, is the best Purple album since Perfect Strangers, IMHO.
Despite all that, I'm actually more of a Mk. III fan, myself. Burn and Stormbringer have long been my two favorite Purple albums, and I can't tell you how many times I played guitar along with Made in Europe when I was a kid. I basically wore out my LP copy of that.