Is it common to ask for reference letters from members of the MSc thesis committee when applying for PhD/Scholarships?
In the UK at least, when applying for research jobs soon after completing a PhD it's quite common for one of the referees to include the external examiner of your thesis (a member of the committee that is external to the institution which awards the PhD). The idea there being that as they're experts in an area in which you've worked and they've assessed a sizeable product of your research (i.e. the thesis), as well as having engaged with you during its defence, they should be in a position to speak authoritatively about your abilities as a researcher.

The professor who has only read your work is in a significantly different position. While they may have the expertise in the subject area, and the familiarity with your work, of the examiner, they've not assessed you in a formal role, nor really engaged with you as an individual.

Of course, your question is about an MSc thesis committee, rather than a PhD one. Without more specifics, you will have to judge whether the involvement of committee members is similar to the involvement of a PhD thesis committee member.