My problem with Class D space is that it seems to impart an
inappropriate comfort level to many pilots who don't understand what
is (and is not) being provided.

This would be because pilots, like all other people, have this idea
that authority and responsibility go together. In other words, if the
controller has the authority to tell you how to fly your pattern, when
to turn, etc - then the responsibility for separation in the air should
also be his. Well, it doesn't work that way. THAT is the primary
weakness of Class D airspace, and it can't be fixed unless you either
make the controller responsible for separation (meaning that unless the
pilot disregarded the controller's instructions, it's controller error,
not pilot error, in the event of a mid-air or near miss) or you give
the pilot the authority to disregard the controller's instructions at
will, not just in the event of an emergency (thus making the airspace
uncontrolled). But while this is an issue in theory, in practice it's
usually not an issue.

In reality, at most Class D's most controllers treat separation as if
it were their responsibility. That means they issue clear and
comprehensible instructions and ask for a readback of the key points,
just as if they were issuing clearances. When that happens, pilots
treat the instructions as if they were clearances - meaning they
question those they don't understand, read back those they do, and
comply - and things work OK - a little better than they would if the
airspace was uncontrolled. Sometimes you get a bad or overloaded
controller, and then things are MUCH worse than they would be if the
airspace was uncontrolled. That's when you get the problems.

I will be the first to admit that I will let a situation that looks
ugly develop a lot further in Class D than I will in Class E or G. I
Class E/G, I know there's nobody looking out for me but me, and if I
don't have a plan nobody does. So when I see things not going to plan
(someone too close for comfort) I take action immediately. Not so in
Class D. Unless the controller has given me reason to doubt his
competence (by doing things like issuing nonsensical or illegal
instructions, chewing out pilots on the frequency rather than calmly
giving them a number to call, and generally acting like he lost SA) I'm
going to assume he has a plan, and I'm going to stick with his plan
until there's just no way. I think most pilots would too. I guess
this is what you call inappropriate comfort level. You are of course
entitled to your opinion, but I don't consider it inappropriate given
the way Class D normally operates. Given the legalities, you have a
point.

Michael