It feels awful to buy these melee upgrades because they are low tier, and thus come with very low stats. Taking them is shooting yourself in the foot lategame, since melee can be tough to guarantee (and especially as people get better at using parries) so it feels like they are a bit of a noob trap. If there were Tier 3 or 4 upgrades for these (like with how Lifestrike is Tier 3) that amount to basically just the same ability but with better stats or some extra effect, they'd be much nicer to take and less suicidal.
For example, you could give Vampiric burst the +20% heavy melee damage and +40% heavy melee distance that Melee Charge has, and that would basically just be like having Melee Charge up at all times with the vampiric burst active for when you aren't punching. Mystic Strike could upgrade into Mystic Reverb, just by adding a signifiantly larger melee damage buff to Mystic reverb (losing the spirit resist debuff, but gaining the huge damage and slow that Reverb has on top of the other stats) and have reverb also work for punching as well as abilities.
For example, you could give Vampiric burst the +20% heavy melee damage and +40% heavy melee distance that Melee Charge has, and that would basically just be like having Melee Charge up at all times with the vampiric burst active for when you aren't punching. Mystic Strike could upgrade into Mystic Reverb, just by adding a signifiantly larger melee damage buff to Mystic reverb (losing the spirit resist debuff, but gaining the huge damage and slow that Reverb has on top of the other stats) and have reverb also work for punching as well as abilities.