For the most part we live in a commercial society where everything is pigeonholed or stereotypically or brought down to a really basic level and categorized.

If you wrote novels it would be the same. It's mostly what is the most basic way to relate to the music that the most amount of people can understand. IE, where to put it to find fans and people who want to buy--or even being an opening act or finding a genre'd record label/deal.

So it's not really bad. It's in fact a very important part of marketing and being successful.

I don't think Evanescence is necessarily 'gothic rock' but for instance, just because it has a guy that raps on it can be very easily categorized as 'Nu Metal' with Linkin Park, etc.

Also one of things Amy does is add some celtic techniques with the rock which it seems you are doing as well. In fact Amy Lee is probably the most famous mainstream female singer who adds celtic type sounds to rock. So, if you have a female singer who is doing Euro-like celtic rock many people will automatically think Evanescence--just on that level alone. Evanesence was probably compared to Nightwish because of this too (even though it's not Rock-Opera).

Another example: if you have really elaborate costumes/make-up you are automatically classed with KISS (ie, GWAR).

So anyways, you always want to sound somewhat like something otherwise you have create an entire audience to enjoy your music/sound because literally nothing is like it. Everyone gets some kind push up on someone else's style or genre.