Unfortunately many British people have the idea of royalty tied up very tightly with their national identity, so any suggestion of getting rid of the monarchy is seen as being treasonous.
You're right about national identity, though, a concept I would happily burn if it were possible. Worldview[1] is a terrible thing.
[1] http://www.skepticalscience.com/Debunking-Handbook-now-freel...
Isn't a British subject suggesting getting rid of the British monarchy basically treasonous by definition?
Even in subjects like social insurance you'll find an abyss among Europeans and US. I believe it has to do with how we grew up.
Personally I'm pro-tradition. If I wasn't, worrying about the complicated but small-impact question of the monarchy would come after issues such as the de facto Christianity in our post-disestablishment country.
It is an opinion that gets discriminated against a bit more than most (along with Anarchism) simply because the Media and the Police don't take either seriously as ideas.
Example: People planning republican protests during the Royal Wedding were arrested in advance and held during the event, to stop their protest being heard[1]. As far as I know, nobody was actually charged with anything, only arrested on suspicion of "conspiracy to cause a public nuisance" and then released when it was all over.
Nonetheless, writing about the idea is perfectly acceptable, and a protest in a less sensitive area / at a less sensitive time would be "tolerated" (not that this justifies the censorship it gets sometimes.)
[1] http://www.theguardian.com/uk/2011/may/01/wedding-activists-...
Maybe it's rarer than I thought to apply this to ones own social ideas, though. Shame.
Did you go out of your way to test the assumptions behind this idea before taking it seriously?