Matthew L. Martin said:
I've spoken out in favor of the Creeping HEROization before, and I will continue to do so--I like HERO, I like d20, and combining the two would make me a happy camper indeed. However, for that to work (or at least to satisfy me), we need to open up the underpinnings of the d20 System.
One of the things that can make a HERO writeup so intimidating is that the system shows most of its work. Everything is broken down to basic elements, with each modifier shown in detail. Once you learn how to use those basic elements, you can do more or less anything within the system's basic assumptions (which are kindly spelled out reasonably well in both the 4E and 5E rulebooks). In addition, the point system allows for what is at least an attempt at precise and clear balance between different abilities. (How well it works in practice is open to debate--after all, it's been over two decades, and there are still arguments over costing STR. But aside from some debatable points or outliers, the system seems to do its job.)
Most forms of d20--especially the 8,000-ton Great Wyrm that is D&D--are far more closed. We get a declaration of 'This is how this ability works', but not 'how we built it' or 'how it balances with other abilities' in most cases. In earlier editions, that wasn't so much of a problem, since they were loose and uneven enough that a group could wing it. Yes, this was like curing chicken pox with measles in many cases, but it did give a sense of freedom that many seem to feel is lost.
As it stands, D&D gives the impression (to me at least) of being an elaborately interwoven, interdependent framework that is so precisely balanced that even changing little details like wealth allotment or class skill access could set the whole structure teetering on the brink of collapse. Whether that's the case in actual play, my experience is too limited to tell, but as Campbell points out, the tone and style of the WotC books doesn't help matters by leaving you high and dry when it comes to the underpinning assumptions and value of classes, feats, abilities, and spells.
Matthew L. Martin