A word for excessive or unnecessary debate on an unimportant issue

Solution 1:

As @DanBron said in a comment, the term bikeshedding is often used for this sort of phenomenon. The term arises from an example C. Northcote Parkinson used in his 1957 book Parkinson's Law: Or, the Pursuit of Progress to illustrate his Law of Triviality. The law states that members of an organisation give disproportionate weight to trivial issues.

Parkinson uses the example of a fictional "Joint Welfare Committee" that approves £10 million for a proposed nuclear power plant in 10 minutes flat, then spends 45 minutes arguing over a £350 bike shed. The design and workings of the power plant are far too complicated for the committee members to have any actual understanding of them, let alone the expertise to discuss them intelligently. So they rubber-stamp the proposal without considering whether the money is well-spent or the plant properly designed. But the bike shed for plant employees is something they can understand and opine about, so they spend a lot of time arguing over its location, color, construction, etc. A detailed discussion of Parkinson's example is here.

Based on Parkinson's example, Poul-Henning Kamp of the BSD community coined the term bikeshedding to describe the phenomenon whereby the amount of discussion generated by a given topic is inversely proportional to its importance. The term has gone on to become widely used, especially in tech.

Solution 2:

It may not tick all the boxes (particularly "a committee of people"), but there is bloviate:

to discourse at length in a pompous or boastful manner (Am. Her. Dict. Eng. Lang., 5th ed.)
to talk at length, esp. in an insubstantial but inflated manner (Collins Eng. Dict., 12th ed.)