Looking back my perspective is very different. First of all, my ideas generated a minor spike in publications for the lab all centered around my work. After I graduated I continued to advise new students to continue what I started.

I now think in these teems, which might sound cynical but simply reflect the vicious nature of academia.

    1. The students given topics, the ones I was jealous of, all kind of sucked. They were given topics to advance a short term goal and gtfo. It may seem paradoxical or cruel but a savvy advisor will maximize both short term and long term gains. I was a long term bet, the others were short term plays.

    2. I benefitted greatly from being forced to identify my own topics. This is the one skill that I use every single day. Every hour of every day. As time goes on the ability to evaluate ideas deeply and with some speed effectively defines what it is I do for a living. 

    3. Students given topics were cheated out of more valuable long term skills for the lab’s short term gains. This is not always universally true, of course. Some super stars really can crank through a deep serious topic quickly and continue on to generate novel research if their own. One such person may appear in a university department once every ten or twenty years, they are extraordinarily rare.

    4. I was well aware of the exploitive nature of grad school, did it anyway with a clear head for what I wanted to get out of it and my only disappointments came from when I giddily let my guard down and expected more than what I already realized would be forthcoming. A specific example, my advisor would use my conference paper acceptances to fund their own personal travel and vacations; I was not allowed to present my own first author papers. Silently tolerating that sort of bullshit, in part, allowed me to graduate.

Edit: I was under the impression that even the postdocs are hired for a specific task.