Maybe not those two companies, but in the past with other "plug-ins" or supplimental programs, they have been bought up and put into "the main program". This means that in the past you may have been able to use that software with a slightly older version, but you then find that the only way to purchase it is to buy a whole program that you don't really need.
I think that supplimental programs can be better, as the manufacturer often creates or allows the creation of importers/ exporters that can be used with other programs. If say Smith Micro bought something up and included it as part of Poser, then that would was likely prevent the use of it with other programs. Also to stay in business, smaller companies and individuals tend to improve and update their software all of the time, many fof the upgrades for free. If someone like Smith Micro bought up the software, then you would have to wait two or three years for the whole program to be updated (not including fixes), and they would charge for it.
In a time where software companies seem to sell us software that that has not even been beta tested properly before it is released, I think that I would rather pay a smaller amount for a supplimental program that if the is a fault, you can report it, and it actually gets sorted quickly, than a program that is supposed to do everything but is useless because of a few faults that take ages to fix.

Like alot of people I got my first copy of Poser free on a magazine cover then later bought the upgrade. I used to do the Same with Flash when it was owned by Macromedia. As far as I know Adobe no longer release an older version for free or at a reduced rate like Smith Micro did recently with Poser 6. How are they going to attract new users into the fold? If you are just starting out with something, you may not want to pay hundreds or even thousands of pounds. Many might not care about having the latest version.

Once Adobe bought Flash, I stopped upgrading and stopped using it. Partly due to the extorionate price differences of some of their other software from country to country. When I wanted to buy Adobe After Effects a few years ago, I found that even taking into account the exchange rate and VAT, that it would still cost me over twice the amount of what it would cost someone in America to buy it.! So two fingers up to Adobe. Autodesk could be heading the same way with their current trend of buying up every piece of software under the sun.

Daz Studio 4.8 and 4.9beta, Blender 2.78, Sketchup, Poser Pro 2014 Game Dev SR5 on Windows 8 Pro x64. Poser Display Units are inches