I agree, I don't think it's fair to say that a 30 min, sloppy, head-bobbing, deepthroat blowjob was bad just because the last 10-20 seconds doesn't include cumming in the mouth. If you're a bukkake fan it may even be preferable to have the dude bust all over her face instead.
We've talked about this before. Personally I've just enjoyed it more when my partner stays down in real life. It takes more skill (How many actresses, cough or gag during this in videos? How many panic and just go to the tip because they CAN'T take it deep?), and it brings a different level of intimacy than just the aesthetic of stuff on her face, boobs, etc. If I went down on a woman and she started to cum, I wouldn't take my mouth off because it feels better to her if I stayed.