I'm not sure what open source packaging projects you're referring to; the image packaging system itself is still quite alive and still open source and available at https://java.net/projects/ips
If you're referring to the general availability of open source software on Solaris, the reality is that the vast majority of compiles and works on Solaris. A large amount of effort has gone into and continues to go into making it easier to build and use general FOSS on Solaris.
In addition to that, based on customer demand and business requirements, FOSS components are integrated into Solaris and updated.
As for "completely ridiculous choice", I think that's an odd thing to say. Solaris has zones, ZFS, image packaging, openstack, and many other compelling technologies (third party or otherwise) that are still being actively developed and improved. Performance and reliability are pretty important attributes for an operating system.
At least for illumos (SmartOS and OmniOS, ...) there is a lot of work happening for web services.
I have been involved UNIX system administration and development for 20+ years. It has never been this lonely in the Solaris community. All of the Open Source packaging projects are effectively dead, due to lack of volunteer. While there used to frequently be Solaris instructions for most Open Source stuff, none of it those docs have been updated in 5-10 years, and nothing new has supported Solaris in a similar time span.
It may just be that Solaris is a wasteland in the space that I care about (web service, primarily). Maybe there are niche markets where Solaris doesn't look like a completely ridiculous choice compared to Linux.