You're absolutel right of course. It's far better to kow the workings than not.
The problem with analogies is that once started, one feels obliged to continue - even if it is somebody else's construct, and an odd fit to one's own point of view. The only way I can apply your analogy to my point of view is to point out that it wouldn't be very useful to the car owner if the mechanic sent the car back with a note pinned to the windscreen saying, 'It's easy', and it wouldn't have been very useful to the mechanic during his apprenticeship HND if the instructors had popped in every so often just to remark how easy everything was.
I suspect that what we're really dancing around here is the question of who these extensions are for. Are they for people like yourself who have already acquired some skill in PHP (and a conscience in tow - good man), or are they also for the unconscionable other - those who come to dynamic pages from a whole host of alternative - but equally valid - backgrounds, atrracted by the marketing material like moths to light?
I have seen people here making incredible progress from a standing start to what looks very much like a good knowledge of dynamic application, which makes me think that we're all in the same boat/car/cabbage, in various stages of the same process. We start somewhere > we learn some stuff > we carry on. We use the tools and knowledge available to us.
So yes - it's good to know stuff and to learn more stuff, - although conscience, like easiness, is another variable I have some difficulty in attaching a value to in this context.