I wouldn't call that "two systems"; statically resolved type parameters are an extension of .NET generic parameters, not a separate system. In particular, a single definition can use both statically resolved and non-statically resolved parameters (e.g. in `let inline f x y = x + x`), and statically resolved type parameters can be used freely where normal .NET generic type parameters are expected (e.g. in `let inline g x = x + id x`). And these distinctions are fairly transparent to users in most cases anyway, since type inference is usually capable of inferring the kind of parameter needed.

In any case, it is true that F#'s type systems has concepts that the CLR doesn't natively support, but I don't see how this demonstrates any weaknesses in the CLR or F#. The exact same thing is true of Scala on the JVM, as far as I can tell - how are erased generics an improvement?