When you're facing flamethrowers, you have to micro your units out of cover or they'll take extra damage. Facing RET Riflenades, you have to micro your units to move a bit after you hear the ping. You even have an extra second before detonation and longer range means longer reaction time. I personally don't see how this is really any different from flamethrowers.
They're even pretty easy to counter compared to flamers by rushing within 20 range (their minimum firing distance).
The difference is parity of input.
One of the strongest parts of CoH's design is it's not an APM game: it's much more about taking
smart actions than
more actions. In most engagements, you analyse the field, put your squads in the right places and wait for the opponent to react.
The problem with the RET grenades is they autofire but they're designed to be dodged. Dealing with these things
is an APM game. Dodging them is trivial: you just tell the squad to move to the side and you've negated the damage. The problem is you have to
keep doing this, whereas all your opponent has to do is position the RET squad and leave them to it.
This degrades the experience into an APM game. Their current design relies entirely on overheating micro: using up so much of your opponent's attention dodging all the autofire grenades that they can't focus on other things.
Some people might not see anything wrong with this sort of thing, but I'm saddened to see it in a game that's
avoided this sort of design in the past and taken steps to remove it where it exists.
In my opinion, the simplest solution is to remove the timers: make the grenades explode on impact so you
can't dodge them and scale the damage they inflict accordingly. If you can't dodge the grenades, then it turns back into a positioning game: you either have to close within the minimum range or retreat.