The Super Saiyan God form accessed through the ritual showed Saiyan capacity for handling that sort of power. Whis' unique form of training drew it out in Vegeta. I fail to see how it's a big deal. I think the implication is very, very much that he'd never attain that form/power even if he spent millennia training through other methods.
I don't get the complaints that Vegeta training with Whis to achieve the form is "lazy" either. It's less lazy to imply that he simply did the ritual, as Goku did? How? Why? Does it really matter?
Whis isn't running a charity. Goku and Vegeta had to beg to become more-or-less his full-time students, and his training nearly kills even them.If you can just train and attain Goldly Ki and become monstrously strong training with Whis' for at least 6 months, then guys like Gohan, Goten, Trunks, Piccolo, have no right not being on the same tier of strength as Goku and Vegeta are right now. They should all be Super Saiyan Blue/Super Saiyan God Super Saiyan tier strength. But they aren't because... reasons. I don't know why none of them thought it would be good idea to ask Whis to train them especially since Goku tells the Z-Fighters that is exactly how Vegeta got so insanely strong in the first place.
You could ask, I suppose, why the other Saiyans don't undergo the ritual to achieve Super Saiyan God, but given that absorbing and maintaining its power seems to be prodigious/training-related as well, the result would be the same -- the other characters aren't interested in working full-time toward Super Saiyan God/Blue. Piccolo might be, but he isn't looking to become Whis' third student and may not have the same capacity for god ki that the Saiyans show. Either way, it's fine.