I do think people overestimate the "issue" with healing.
Low levels, 5e in combat healing is often equal or stronger than 3e healing. Its not until 6th level that it starts to slip away, and really more like 8th level where it starts to become really noticable. But also 3e characters have a lot more hp in general (due to con boosting items practically being a staple), so I would argue that 5e healing as a % of total HP is probably still higher than 3e. But.....5e casters have fewer slots, so the amount of healing as compared to your % of spell slots used is more penalizing on the 5e side.
Now 3e heal blows away the 5e version, but again we are talking levels that most players never or rarely see, so if you consider the "sweet spot", combat healing is overall still pretty good.
But.....it can be better!