Wrong. You may be able to not orgasm when you don't want to, but that's just you. I have had BDSM sessions where the model legitimately did NOT want to cum - and she did fight valiantly, for over an hour and a half - but eventually she lost the fight and the sensations from the vibrator overcame her will to not orgasm.
And jesus christ, did she scream. The poor thing couldn't walk for ten minutes afterwards.
Back to the OPs question - almost all the models you see in bondage and tickling videos become rather horny during the shoots, between the bondage, the helplessness, the verbal teasing, the ticklish sensations, and the exhibitionism. As a result, the models thoroughly enjoy the "forced" orgasm, on top of the fact that it usually gets them paid more for their time.
The appeal, as far as the people watching the videos is concerned, comes in when you think about it this way - many, many, many of the people here on the TMF have at least some aspect of BDSM in their kink-list. As such, bondage is incredibly hot. Obviously, orgasms are also incredibly hot, so what happens when you combine the two together? You have a screaming, writhing, moaning man or woman whom you know is feeling incredibly intense sensations, pulling at their bonds, unable to escape. The vibrator is in a super sensitive spot, and unlike when they may be masturbating or having vanilla sex, they cannot control the rythym or pressure, which means they have no say over how intense or long lasting the orgasm is.
It's a power play - an audible delicacy - and a visual treat to watch a helpless victim cum their brains out (often more thasn once), without being able to do shit about it.