I occasionally use `!` as an escape hatch from the compiler's inability to reason about code correctness. Assert signatures in TS 3.7 will mitigate this issue significantly, but until then, I'm bangin'.
Yeah there are still many flaws in typescript's null checking, even in quite pedestrian code. The ! operator isn't evil, far from it, it exists so that the compiler can be more aggressive at checking nulls knowing that programmers can always override if it makes a mistake. I would never rewrite my code to avoid ! per se, I write it to be most readable to humans, if that doesn't please the compiler then so be it.
