Yes, introductory clauses should be offset with commas. Some call clauses that begin with if, when, where, etc. conditional clauses.

Even when minimalist principles are adopted, these clauses really should be offset.

Consider:

If not, we should close them.

If not we, then I should close them.

Being clear about when introductory clauses end generally increases reading speed by lessening the amount of guessing and rereading that must occur to decode the correct meaning. There are many good reasons for enforcing this particular standard for punctuation.