Let me take a crack at this (in English) since no-one has addressed this.
Top consultancies typically want the best people regardless of their background. Yes, some roles are reserved to individuals with a particular expertise set, but I'll ignore this scenario and focus on the general case.
Would having a consulting internship help you? Yes, definitely: it'd show you have expressed prior interest in consulting, probably practiced case interviewing, and experienced it first hand. So if you still want to do this, there's a good chance you would stay around a little longer. At the same time, they will wonder why you didn't get an offer already if you were this good.
Do you need a consulting internship? Absolutely not. Many of us got into consulting post-MBA without prior consulting experience. Indeed, this can be a strength as well, since we have (hopefully) demonstrated successful real-life experience. You have worked at large and/or well known companies, that's a good start since they are unlikely to hire just anyone.
If you want to try consulting, the best time is now. Go for it, practice, apply, get in, rock it. Don't let others tell you what you should or shouldn't have done before - but be ready to answer why consulting, why now.
Hope this help. Good luck!
