Don't underestimate the productivity boost provided by the little squiggly red line. The fact that your tooling will stop you from ever passing T when the expected parameter is Collection<T>, and that this "rescue" involves pretty much zero cognitive overhead, is invaluable. When I work in a statically typed language, I find that I pretty much never make "head-desk" type errors, and despair at their reappearance when writing... javascript.