Another important thing to note here is that not all transgender people want or need to have surgery. The first non-medical usage of transgender even excluded people who wanted or had surgery, and exclusively used by full time crossdressers (read about Virginia Prince for more on that).
A good reason why trandgender should be kept as an umbrella term is because transphobes do not care if you have gender dysphoria, don’t identify as male or female, or just dressing up as the opposite gender because you like the clothes. We are a small enough group as it is, we need to keep working together if we are to fight for our rights, not split up into smaller groups that are weaker.
