I don't think he's as much of a must have pick as he used to be and I think he's engaging enough to play if you wall climb to get to places enemies don't expect whilst still providing your team heals and speed.
I think it's more about the person playing it, sure you could stay on the ground and do a good enough job but why not try a little harder and do a little better? You don't have to go to DSPStanky levels and only go for individual flashy moves but theres lots of places on lots of points lucio's can hide and provide healing.
I also don't think teams punish you as much as you think Sandshrew for going for boops, honestly more often than not, as long as you dont just run at them in a straight line, they hardly even notice you. There's so much you can get away with quite often I'll dive past the rein shield and just boop him into my team, obviously relies on a few factors but that's usually a free kill the team gets and it feels impactful.
The only thing I dislike about lucio is his ult. It's the only disappointing bit of kit he has, for a character all about engaging and disengaging his ult is a shield for a couple seconds. I'd rather he did something different than that but I'm not sure what. Just something that fits into his playstyle and purpose.