Oh, that one!
I don’t know what it exactly is (Rod Evans’s voice?, the poor man’s Vanilla Fudge over-arrangements?, the less than state of the art production and recording?, the lingering 60ies pop influences?, the many covers, all of it?), but all of Mk I’s output sounds firmly entrenched in the 60ies for me, quaintly old-fashioned already for 68/69 when it came out. Purple only began to sound like the 70ies (and some people say: opened a new sound era though they weren’t the only ones) with
In Rock (recorded in the second half of 69 and first half of 70). The first three Mk I albums all sound dated,
In Rock sounded like the dawn of a new music age.
Visually, the Mk I line-up was out of touch too with what was going on at the time. When Ian Gillan first met Ritchie Blackmore and Jon Lord in 1969 he was amused by their obviously expensive, but no longer really fashionable or cool Carnaby Street dandy style clothes and their still coiffed-backcombed/teased hair. Having spent a lot of time in America (and there especially on the West Coast) where Mk I had been more popular than anywhere else, they had totally missed the changing vibe of late 60ies London.
By 1970 they looked like this with Gillan and Glover having joined.