It's not just comfort tires, it's dealing with visibility and changes in grip in dry spots under bridges and in tunnels. It brings some much needed variation to the stale weekly roster. That gif is from 2 years ago
The only rain track with varying wet/dry is Tokyo Central due to all the bridges and overpasses. All the other tracks are just static, same grip reduction everywhere. Like Pigems said, it's basically just like putting Comfort Extra Hards on your car. Yes I agree visibility is a challenge, but with radar you get a bird's eye view that you don't get IRL anyway.
Comparing to ACC, we don't have:
- Wet lines (crazily, back in GT5/6 we have this)
- Aquaplaning/puddles
- Dynamic conditions (IRL the best wet weather drivers are very good at sensing varying grip levels corner to corner, no such thing in GTS because you can practice infinity laps in the exact same condition)
- Transition from dry to wet (in ACC we can pick up marbles to act as rudimentary "grooves" for your slicks, only for a few laps because the marbles get washed away soon)
- Transition from wet to dry (overheating rain tyres and having to go off line to cool them off)
- Pointless having inters/full wets because conditions are static anyway - just have one compound called rain and we'd be none the wiser
- Rain tyres are actually very grippy IRL. The compound is very soft, the tread blocks are designed to flex to grip the road and it's designed to operate at lower temperatures. In GTS it feels rock hard and even less "rubbery" than the dry slicks.
So yeah, the rain driving just plain sucks in GTS. It's really only good for photomode. If you drive an FR Gr.3, you might as well stay home because the MR have overwhelming advantage.