Now I don't understand what you are saying. Are you under the impression that India wants Pakistan back inside? That is not the case at all. May be there is a 1% or less crowd that may feel that way but I haven't come across ANYONE who wants that.
Now. many Indians, including me, are angry at Pakistan for attacks in Kashmir and Kargil etc. That is different from wanting to bring Pakistan back.
Of course borders change over time.
People in India (who have some knowledge of politics, defence etc ) may not be eager to bring back pakistan to their fold. But then again they are not averse to that idea either as far as i know.
Then again, there are many who severly oppose that as it would increase the influence of muslims in the sub-continent.
Irrespective of all this, historically, culturally, racially etc etc the entire subcontinent is very diverse. North india is different from south, North east india is different from rest of india. Even during british india, pakistan was/is different from rest of india / even bangladesh. Even within current day pakistan, there is lot of diversity. But amidst all this diversity, there are quiet a few things which would overlap as well, may be in terms of language, food or culture. Anyway, this is a very complex topic and might need a seperate thread.