See, I don't mind raid starships coming in and killing everything if you're not prepared for them. My only complaint is that there's no really good way to prepare for them. Any fix that's going to defend against them without the player doing anything, like making certain structures immune to them, takes away strategic variety. And any fix that warns you ahead of time of their approach, like a wave warning, still leaves you micro-managing to deal with them and it doesn't really give them a chance to slip in and kill things when you're unprepared. You'd have plenty of time to move fleet ships in or build turrets.
That's why I'd still like to see some kind of defense that you can build ahead of time, giving you strategic pre-planning, but that doesn't completely deal with the problem without your intervention. Thus things like a distraction unit or a weaker shield that can't be pierced but which alerts other ships and players when it's attacked. These keep you from losing something instantly, but don't prevent you from losing it if you don't act further to protect it and weren't already ready to deal with threats on that planet.