It's called Steampunk and it's been around since forever.
Indeed, the concept of mixing fantasy and technology is not something no one has done before, and if you ask me, people who think it can't work just need more experience with it. Now, if you've tried various works that are based on the premise and widely regarded as good to those who like the concept (The key here is that they have to be seem as good. If everyone agrees they're bad, then maybe it's not so much that the premise doesn't work as just that it was handled poorly.) and still don't like the idea, that's perfectly fine. Some concepts just won't appeal to everyone, but if you're completely disregarded a genre you haven't really given a chance, then how can you really rightly say it "doesn't work"?
I would gladly play such a game, if it were good, it comes down to a question of how well it's handled. I agree, of course, that it wouldn't fit in the Elder Scrolls, but that's because the Elder Scrolls already has a fairly well established setting and feel, and guns just wouldn't fit with the feel of the setting. If you're making an original property, yo can do whatever you want with it, you want to put guns in a fantasy world? Fine with me, if I like the finished product, I'll buy it.
As to whether I'd play a game from Bethesda based on such a concept that was not the Elder Scrolls, if it appealed to me, than yes. I don't want guns in the Elder Scrolls, but it's not like the only game Bethesda can make is the Elder Scrolls, and Bethesda already owns another franchise that features guns, you know, Fallout? Sure, it's not fantasy, but since they have franchises both involving magic and guns, they could use lessons they learned from developing both franchises in the new game. And the way I see it, if Bethesda decided they wanted to explore such themes, developing an original franchise revolving around the concept would just allow them to do what they want without adding such things to established franchises they wouldn't fit.
no. the topic is asking WHY mixing magic and guns is percieved as unacceptable or not possible. as well as if people would play an rpg that mixed the two.
I'd say the reason it's not more common is for the same reason why 99% of western fantasy takes place in what might as well be the exact same psuedo-Medieval generic fantasy world, with just some names changed. Because either many creators aren't creative enough to pull off something different from the norm well, or they think that people want to see the same tired concepts again, and again, and again, and again, and again until there's simply no way you can even hide the fact that there's nothing creative about your ideas, rather than seeing something original. And since having a setting that combines technology and magic would be different from the norm of faux-Medieval fantasy, creators don't want to do it.