It did not explode when it landed. It exploded after it landed. This is an important distinction, because the latter is a thousand times harder to accomplish.
Let's say they permanently remove one leg and it now always tips over on landing and has no stable landing configuration. Could they bill that as a self-landing rocket?
The point is that the ability to land is much harder to develop than the ability to stand up after landing. Improving the leg locking mechanisms is relatively trivial compared to developing the ability to turn a booster around in space, fly it back to earth and land on a floating platform.
If I was involved in SpaceX then I would be proud to have helped solve such a tricky problem, and optimistic about fixing the far less difficult leg locking problem
I agree it is a big achievement. I just wouldn't call it a successful landing. If the moon landing had involved immediate tipover and explosion with a leg that didn't deploy, I think a subsequent landing would have been considered the real first successful landing.