I think the version she does in the Mikhailovsky version isn't invalid given that I'm pretty sure I have seen other dancers do it too. For example, Nadezhda Gracheva (variation starts at 1:24, hops begin at 2:22). Of course, whether a dancer does it because she simply can't hop or because she feels its adds value artistically might be different things. But if a dancer is all in other respects a fine Giselle than this modification (unlike hopping the whole diagonal on demi-pointe), for me personally, would be acceptable.