Well, I've seen people build fantastic essays around making the choice to go all out on a senior thesis (specifically Booth Essay 2 about taking a risk). But you will have to be the one to shine a light on it - it's not something adcom readers will go crazy over on their own.
There is something to be said for taking this one year of your life to master something. It's not something common to US college students anymore - where they can leave school knowing more about a subject than literally almost everyone alive. It's pretty cool and trust me, it won't present itself again. If you are feeling it in your bones, do it man. If not, well, it's not going to come back to haunt you on the apps so go forth and prosper.
Ultimately, I guess what I'm saying is that this is a life choice and don't let minor MBA considerations govern it.
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