they are not hard once people get it in their head that standing in red=bad and that they have to interrupt hostile casts
Telegraphing the red means that it has to be more tightly balanced. Too much warning = too easy. Too little warning = too hard
The problem with this is that normal latency can cause significant issues for some and not for others. I don't believe it is as much of an issue in systems with less obvious tells because they don't need to be so stringently and consistently balanced to present a challenge.
Official forums are going to be a massive bitch fest within weeks of launch. If you're reading Scooter by far the best move you could pull would be to close the official forums - period. I'm guessing you probably won't, so good luck with that.