Show the vote split by default

I think performance is still a major concern. As you might have read from those other posts, the post score is kept as value in the posts table. That value is pre-calculated based on the upvotes and downvotes. That means that it doesn't need additional fetches to get the post score from the votes table.

You could say of course that the team could add two more aggregated columns in the posts table, one for upvotes and one for downvotes, which are calculated the same way the current score is. I am not sure what the impact would be in ways of performance or development time, but it seems the only feasible way to improve performance that much that it can be shown to everyone.

On the other side, I don't mind that new members don't see it. We don't want to confuse them too much with the way SE works, they are puzzled enough already. Step by step they are made familiar how things work. Showing too much information might not be a good idea for that reason.

I don't agree +35/-25 is an awful post and the reputation algorithm does not either.

You have to have the rep to see up and down. It is a cleaner UX withOUT the split (IMHO).

I mostly disagree with your premise. There obviously is a difference between a question scoring +10/-0 and a question scoring +35/-25 but not enough of a difference to be adding more features and UI for new users. It's certainly useful and interesting, but it isn't essential.

Post score is a good quick and easy measure of a posts quality, but it doesn't, and shouldn't, tell you everything. A post should stand on its own merit and you don't need to see how many specific votes a post has to determine its usefulness (the only exception is possibly meta posts where a consensus through votes is important—but that's not what this request is about). A single score is also much easier to process than having to compare the ratios of two scores across different posts.

Arguments that post score alone isn't enough to tell you the usefulness of a post are expecting too much from the score—vote counts certainly tell you more, but they're in no significant way more reliable.

The ability to see vote scores is also the main part of the Established User Privilege which is the first "milestone privilege". The whole reputation system is built around unlocking features at set targets (whether that is a good system or not is besides the point of this question) and as a target, unlocking vote counts is useful enough to be a "milestone" feature but not essential enough to be needed before that. If vote counts were always visible there'd probably need to be something to replace it as the first "milestone privilege".