What advantage do you think a protist would gain by having a unicellular, filamentous, or colonial form?

By having a unicellular form, a protist will gain two major advantage:
1. It would be able to reproduce on its own, asexually without having to look for sexual partners. It will be able to reproduce by binary fission, multiple fission or budding.
2. It will benefit from a simple body system that does not need system specialization. Having specialized systems with many parts can results in some of the system having problems at times.