thomq: To me it's simply a matter of position, personal interests, priorities, opportunities, and so on in general.
I sometimes think of it in this way: There's a huge structure and it's rather magnificent, or at least to those who created and maintain it. Unfortunately, it's the maintenance that distracts from the priorities of further progress. Maintenance or progress? Bail water from the boat, or sink to ocean floor while patching the hole, or jump ship into lifeboat or a makeshift raft and start building anew upon that?
Of course, it becomes such a spectacle that outsiders begin to talk about it and draw attention. Sometimes a person will just sit around and watch, and criticize, and Monday-morning-quaterback about it, but never participate.
Then there's sometimes when a person will acquire a reputation (f.e. marketing products) related to the events of such a spectacle, such as participating in entrepreneur activities, as a conman, for a charity, for journalism, etcetera, etcetera.
As such, a person might buy into some of that, by means of accepting something either purchased or freely, either physical or just story.
So, it seems to me it's a matter of position, personal interests, priorities, opportunities, and so on in general, like for anything else in life. Of both perspective and participation/attendance.
If you don't maintain your projects, they will break. From a person with a maintenance background, that's the truth. However, it's not a choice between "Maintenance and Progress" as you state, but rather a choice between actual designed functionality vs new shiny goodness.
So far, this site update has followed suit with the rest. Fix some broken features, change the way things work, and completely break something else. They can't seem to get a grip on their own system, and rather than live testing changes, they simply make a few, and drop them over the old system. The forum, for instance STILL doesn't have a mobile version of the menu. Despite all the changes made, it is still the web version of the menu (no hamburger dropdown, but the clickable links at the top that are useless if you zoom in). The main page and library etc. have the dropdown menu I can tap and navigate. Why is the forum menu different? That's a minor gripe though. My bigger question is why can't they seem to fix most of their problems in one go, and instead have to sacrifice other features to get some fixed? Because the web dev team is either borderline incompetent (not a stretch since anyone wanting to work for GOG has to physically move to Poland, even in an online era; therefore their talent pool is drastically reduced to choose from), or the old system was designed so poorly by older incompetents that they can't figure out how to fix it, and designing a new site from scratch is either not cost effective or is too difficult for the talents of their current staff.
So it comes down to a matter of priority. These fixes implemented on the client side are small, fix functionality and took relatively little resource to develop. The surprising part is that basic functionality isn't a priority. I hate to use the cliché, but Steam doesn't have these kinds of problems. Their site is well developed and all the visibly intended features work. This site feels like amateur hour most of the time, no matter how shiny and pretty they try to make it to disguise that.