There was obligation to work, unless you were sick. You could choose your trade, and if you were lazy/stupid/handicapped you were offered job that weren't demanding. Salaries were centrally planed, as was prices. The end effect was - less than 1% unemployement, huge drop in efficiency, no creativity boost to speak of.
I wonder if BI experiments suffer from observer bias - if the experiment was going bad it would be stopped, or at least people participating may think it would be. It's usually small community so they know who isn't working, and they can influence him.
If you were to introduce BI on huge scale, in a way that people take it for granted, I think the results would be much worse (and much more realistic).
People react to incentives. In the Soviet Union, "they pretended to pay us, and we pretended to work": although workers certainly received money in exchange for labor, increasing the amount of money you had did not typically increase the goods and services available to you, as the price system was so messed up that real prices were measured in waiting times and political favors.
A basic income avoids that trap because it leverages the distributed computation of the market to set prices. People will still be at least as entrepreneurial as they are now, because there's the opportunity for huge, outsized profits for both the entrepreneur and the provider of capital.
Also note that most salary workers nowadays make far in excess (typically 50k+) of what the minimum income would provide (on the order of 10k). Most of us here could work for a year, survive on what the minimum income would provide, and then have enough savings left over for nearly another decade at minimum income levels. But we don't do that, because we want more, and that wouldn't change with a minimum income.
The core premise and compelling logic of BI comes from the fact that it is simple, not-gameable, and, most importantly, doesn't have huge disincentive effects at the margin as benefits phase out.
PER sounds like it runs headlong into all of those issues. By the standard you're using to critique BI using PER, I could just as well point to PER to critique markets as a whole.