Big hard No for me.
The math is clear, even on melee it’s not that much of a malus and faster unit healing is a powerful bonus. This promo does not need a buff.
The problem is different play styles. Especially when having a couple of strong units the healing doesn't happen fast enough to warrant keeping track of where the healing units are and placing them in the middle of your army. You might take a city in 20 turns, or you might have an army diving into another city because it's just too tight an area to fit your entire army
I've encountered many games where sea based units are not viable because of the ai's strong naval presence. (I proposed rebalancing or adding more naval diversity so you can't just win the sea by having 30 melee ships) So having a large land army is a faster way to take a city than first achieving naval superiority. But this means crawling through tight 1 tile spaces sometimes, one unit at a time, which is terrible for the healing promotion, when you would rather work towards the "heal every turn despite action" or " shoot over obstacles/one extra tile away" promotions, especially
in those tight spaces.