I wouldn't say that rape is a planned act 100% of the time.
"date rape" is not rape, so much as it is sexual assault. The terms are so muddled. Rape by definition means unwanted sex attained through violence or the threat of violence...but many rapes don't involve coitus whatsoever, but are often violent and/or demeaning - control of one person over another physically. This sometimes means coitus...sometimes. Rape is often what people think of when they picture the stranger leaping from bushes etc...
Date rape is often misinterpretation of intent and expectation. The assaulter wanted to take the situation to the next level physically, but the assaulted did not. The assaulter did not take 'no' for an answer. As such it's an assault (forced and often dealing injury in the process). - it get swept into the same definition of 'rape'.
Statutory rape is another story entirely. Both people involved may very well want to have sex, but one or both are under-age. This is usually filed by one of the parents against their child's 'assaulter'.
Sexual contact while under the influence of alcohol, drugs or unconsciousness is considered rape as well..because one or both people involved were in no condition to give consent. It should be considered sexual assault instead of rape unless one person planned on using drugs, alcohol to render the target pliable'.
I think that it all boils down to intent and planning..especially in the case noted. The assaulters knew her sexual-identity and picked her because of it, took umbrage to it..bullied her ahead of time, planned a location and time to assault her and went through with the rape.
As such, the crime is that much more vile. Sentencing should take that into effect.