Had uni exams the past couple days, sorry for the late reply.
The first thing I should say is that Tempus wasn't designed to be the timer for all of jumping and speedrunning, and we don't plan it to be. We have a network of servers that deliver the experience that we want, and there are lots of other servers (or offline jumping) that deliver different experiences.
If you want an entirely consistent jumping experience for everyone, you will probably have to find a way to mod tf2 and do all runs offline. This isn't the solution we wanted (or know how to do), so we have an online network. Once this was established, any player that runs online is immediately disadvantaged to someone running offline, due to ping, server lag, time available to spend on a map, etc. So I don't see offline runs comparable to online runs, and it isn't something in the scope of what Tempus should achieve. Times on Tempus are meant for internal comparison, this is why we don't accept submissions of other times. I don't want a top times leaderboard that was plagued in the same way the skillsrank one was, where its times were more comparable to offline that Tempus ones are.
So with comparisons to offline jumping out of the picture, it became a question of how do we make the online jumping experience as good as possible. This was through creating better consistency (no doors, breakables, solly and demo HP regen). As for map ending zones, this has been one of the most controversial things. It was done to create consistency across the maps, you hit the final platform and your timer finishes. The aim was for all players to not have to worry about where the author has put the finish cap, what size the cap, or if there even is one? I personally believe establishing certain standards are better than simply following what has been done before for the sake of it.
As for 4starters, the course start zones are to avoid players accidentally triggering them out of order, and cancelling their runs (which I had many complaints about after they were initially zoned in the 'normal' starting positions).
As for your mention of other inconsistent levels, I don't enjoy them. Jump_aris last level comes to mind, where you have to shotgun twice to open two doors then fall and do a sync. This is a major pain online with lots of people. My approach is that i've only removed buttons/doors that are in level transitions, not levels themselves. Maybe this needs changing, I'm not sure. I think I'd prefer maps without them (granted I am guilty of one button on void), but that's a personal preference which I'm not going to make major changes based on. On the note of that, I'd like to think I have been reasonably flexible in the past with changes which have a strong opposition. For example, pre-speed limiting was something I was pushing for initially, but we did not implement because of feedback. In hindsight, it would have been a bad choice so I'm glad people spoke up.
I don't see how the casual plugin argument relates at all. If anything, having online runs which aren't comparable to offline runs makes it much harder to get away with a TAS run (this is assuming they can only be done offline, which I'm not sure has been confirmed or not).
"at most, if theres no intention of making these changes, tempus runs(on edited maps) shouldnt be counted in any kind of leaderboards, let alone wrs."
I have no idea what leaderboards you are talking about. We have internal leaderboards on all servers, and that's about it. Feel free to link the Official TF2 Jump Community Speedrunning Leaderboards™ that I'm somehow missing. Joking aside, it reiterates my point that Tempus isn't the be-all and end-all of jumping. We simply provide a network of servers with the best experience we can create. I still strongly believe there is a need for skillsrank, offline and other jumping experiences to co-exist, but only to that extent.
Apologies for the long-winded response. I get frustrated when people have the expectation of Tempus being the single, perfect saviour for all of jumping. There are too many issues, limitations and inconsistencies with TF2 to have anything like that, so we just try do our own thing the best we can.