Why does IIT Bombay have so few GSoC acceptances compared to newer institutes like BITS-Goa and IIIT-H?

First of all, neither ACM-ICPC nor GSoc truly defines a person's worth or skills. I have seen many IITians mocking GSOC claiming it to be worthless. The truth is quite different. GSoc is one of the best opportunities for 1st and 2nd years, and for anyone not interning at Google, Microsoft Research, Stanford, ETHZ, and similar companies. However, GSOC required a lot of dedication and commitment. IITians prefer easy jobs that require minimal effort. This is the reason they prefer foreign internships that can be easily sought because of the IIT tag. 

GSOC belongs to an altogether different league. You have to spend months contributing bug fixes to a project and staying dedicated over a long time. Your school name has no value unless you work hard to demonstrate your dedication.

GSOC is worth a lot and IITians are usually misguided by their seniors to believe the contrary. One gets to design a good project proposal, compete with everyone from all over the world and then implement it. This is way better than the web application development one does at Goldman or Morgan or Yahoo. 

Usually, institutes like BITS Goa and IIIT-H are only after success and thus try to compete with the big names to gain fame. So it’s better if people with privileged backgrounds and institutes make their names for themselves and stop dominating those that have earned their worth through efforts and not just tags from big institutes.