Why not to do it:
Rather than treating the MBA as a label that will look nice on your resume, and it will; it is better to ask yourself what you really want to do with it. As you mentioned only you can really answer that, but I would imagine you enjoy coding enough that you want to combine the two in some way. There are after all too many empty suits with MBAs out there with nothing else to offer (without knowing them this sounds like your friends to me), and are half the problem with everything that's been going wrong lately. You're clearly thinking whether you'll still enjoy the job as much 10/20 years down the track which is wise. The financial factor is not insignificant, but if you can see yourself content with 'just' coding for the rest of your career then that's good... and you'll do well enough out of it surely? Definitely don't do it just to keep up with your friends.
The other slightly different reason against doing an MBA is if all you want is the knowledge (sans prestige), then find out what the course texts are and read them. Much cheaper. Under no circumstances go to a no-name business school. Only because those of us who went to the other type consider them near worthless (tough, but it is the new school tie). INSEAD is a good choice btw, excellent even. The reason there are business schools better than the others is partly the teaching staff, but mainly the caliber of the students they attract. The actual course content is not exactly rocket science; it's the competition from your classmates that take simple assignments and turn them into death matches that separate the best schools from the rest. If this doesn't sound like fun to you, then another reason not to do it.
At MBA school you would instantly pick out the ones who want to get into investment banking (every finance unit, even doing external finance qualifications in parallel). Then there's the management consultant route (...well doesn't everybody? but the keen ones will organise themselves into case study-study groups within a few months/weeks of the course starting to get ready for internship interviews). There are other categories, but you get the idea... if you don't see yourself in one of them then you should try to get a good idea of what you want to do with it; other than get a job with a fat paycheck. That would probably happen, but you might not only just be miserable, but turn into something you hate.
Also if you are only doing a MBA to become a project manager. Then no, not a good enough reason.
Why you should actually do it:
Why I would do it is if you want to do more than being kept in a career box and worst of all used as a 'resource' by a MBA-type. Then put away when we're no longer needed. If you stay a pure coder/technologist then you will always be vulnerable to that. If you can see yourself wanting/needing to have a greater say in how things are done in your place of work, then the MBA is going to give you the toolkit to help you do that. I'm not saying it's mandatory, there are other pathways obviously. But this one is not going to hurt.
What I would ask yourself is once you have all that extra knowledge, what do you plan on doing with it? It doesn't have to be one single thing, you're still at the start of your career, so there are plenty of options. All I can leave you with is my personal credo... If we are going to win the war against true evil, then some of us are going to have to cross over to the dark side.