I'm very involved with (lately less so, been busy) and IMO you're pretty accurate.

Some more details: Replacements for autotools often only handle the simple case. Widely known that autotools is difficult, however, the replacements cannot do what the GTK autotools is used for at this moment.

For the compiler: I think the Microsoft compiler is holding us back? Further there are two important parts: glib is used almost everywhere, so you have to be very strict in what you accept. GTK+ should be more easy going. They did add that support for (IIRC) automatically freeing variables.

Tied to Red Hat is very unfortunate. However good willed, it is better if there is a group of similar sized companies. I'd wish there were more (free software) companies the size of Red Hat.