Is there a reason to spend 4 points on a new mutation? This is driving me crazy.  I've been watching twitch streams and I see the majority of people playing spending all their points to buy new mutations instead of upgrading old ones, something I've never felt the urge to do myself because four levels of upgrade just seems objectively better.    Now I understand the appeal for esper builds, since the ego bonus means that new mutations come in already fully powered.   But even people playing physical builds with no ego seem to prefer to buy new mutations.   What am I missing here?