IMO its the type of them that has changed. i truly don't think the true "flowerpot" green (IMO ugly as heck) goni's have gotten any easier to keep in captivity, but in the same breath, i seem to hear more and more stories of reefers keeping the original green ones for years with barely any issues. the red and purples and blues that have been popping up lately, I THINK are slightly diff species than the original ones that we know, and its shown by the length of polyps, shape of each head, and even the tips looking different. i even dealt with a few "jewel" goni's that were a decent color but didn't have "fingers" that extended over a qtr of an inch, and i found out that's basically how they look.
in no way at all am i saying all this from anything else than opinion and my own research and experience, so take it with a grain of salt. but with aquaculturing much much more prominent in this day and age, i feel so many of the gorgeous ones, much like forrealb50's, have more likely than not been cut from a colony that has been in captivity for a while, which also started as a frag from a captive colony, and so on and so on; instead of jus being plucked right out the ocean and ending up in a home tank. this is probably why we have seen such crazy "rainbow" and nice yellow colors that were jus nonexistent a few years ago.
that piece u have is beautiful, and i hope it survives for many many years, nice pickups!!