It's not poorly written software if it's is old. Likewise the y2k bug is often declared as bad programming, but at the time the software with the y2k bug was written memory was measured in kilobytes and a lot of accounting software and banking software was written in a time when 64k was the norm. Oh, and I'll tell you now I know of at least some accounting software that is based on code written for the 8088 and has been wrapped and cross compiled so many times now it's unrecognisable. But I know that 40 year old code is still there.
So 2 digits for year was best practice at the time and at the time software vulnerable to the 2038 bug 32bit epoch dates was the best practice.
Now, software written today doing the same, could of course be considered bad, but it's not a good blanket statement.