Designers steal ideas? Openly? Umm where do I begin? I mean to some degree it falls in a legal "recipe copyright" zone...That I understand, and as someone who has copyright in multiple countries, I can say that openly admitting to stealing other peoples IP is an unwise move.
I will refrain from any further Ted Talks on the subject. Instead I will counter that by staying away from other peoples ideas, then the expression of my game becomes pure creativity, and blends in with the needs of the gaming system as a whole. Not relying on DnD is a double edge sword, while open liscence rules are not available, I am not held down by any DnD expectations, rulesets or even methods of expression. While some may look familiar, (there is only soo many names or labels for Strength for ex), by and by the product has it's own unique feel. If you play my game like you do Dnd, you will most likely fail.
That said, I openly acknowledge that 90's games may be different and that rule's light may be different. It still does not cause me any reason for excitement. It stands to reason, the less rules you have, the more guessing, and just making it up as you go, you will have to do. I can invent a game that determines any and all successes and failiure with the toss of the coin. I can eliminate stats completly and turn everything otherwise into a coin toss.
To some, this may be fun, but it will lack getting familiar with the mechanics, the player will lose much of the sense of mastering a new skill, or researching that ability through thier own efforts. There are soo many treasure troves of rewards hidden in my mechanics that you can almost feel the success of your character. Rules light systems do not carry that same enjoyment for me and nor can they if they are light.
Finally I understand not all will love this approach but for me roleplaying is the easy part, but do your rules reflect life, as a personal observation? Do they truly allow a player to become not just powerful, but goddy? And in doing so, does it still make you earn it? Do you follow a path to godhood? I mean my gaming group just celebrated 10 years of consistant every weekend gaming. My second group is back for its 5th or 6th year. You don't keep people that long over nothing.