I can't believe it's been 30 years already since the plane crash! Of course I didn't see it until roughly 1996, since we were a few years behind at the time.
I have mixed feelings about the whole storyline. Yes, it was successful, and well done, but it changed Emmerdale forever and the show has tried over and over again to replicate that success, with varying results.
As for Kathy returning....what would be the point? Don't get me wrong, I loved Kathy when she was around, but she's been gone for over 20 years, and the village is not what it was when she lived there. Practically everyone she interacted with are gone, the only real exception being Kim. And I wouldn't trust the current writers to know what to do with her. I would rather have her memory intact than watching her get destroyed, which she undoubtedly would be. And then there's obviously the issue of Malandra Burrows' health. She was battling breast cancer last I heard. Hopefully she's on the road to recovery, but I haven't been able to find any news about that.