My guess is people aren't complaining about it because most people seem to think it looks cool.
If it wasn't for the effect, I wouldn't use the spell. It would be more fun for me just to kill conventionally with attacks and warps. But I'll definitely want to use it and have partially "decayed" mobs running around . Don't really care that it doesn't look like real decay, or if it's weird on mechanical enemies or anything like that. It would be cool if more realistic, but I guess I'm not that picky.