From an undergraduate standpoint, there certainly isn't a lack of interest in the program - the intro CS course is consistently one of the largest undergraduate courses. Though the smaller department size means certain courses aren't always offered, the quality of instruction tends to make up for this (as well as the possibility of cross-registering at MIT). A side effect of CS being an up-and-coming department is that many CS undergrads come to Harvard intending to study something else (say math, physics, or economics) and thus bring with them their diverse interests and skills to the classroom.

This isn't really a problem because Harvard and MIT allow students to cross-register (for up to half of your credits, the same as if you transferred from another school, although I'm not sure if the rules have changed in recent years).