The choices being made to "fuse together" formulas or not is sometimes a bit surprising to me. I am getting used to them, but that is not to say that I embrace them :

Writing a lot of exercises and solutions at the moment, I am often in the process of adding to the left of some formula, some other things, definitions, other arguments... If the cursor is just to the left of a formula, then hitting $ does not begin a new formula, separate from the one to the immediate right, but instead the cursor goes inside the existing formula to the right. So in this case, $ is redondant with the right arrow key. Not a big problem obviously, as I just need to remember to place some separation, such as a space, before hitting $ (because after it is too late, the formula cannot be split into two separate formulas). Still I would prefer in this instance the $ key to begin a new formula, distinct from the one immediately to the right of the cursor.

At the opposite, I use a lot of copy-paste in formulas (this is really great), and if I want to extend a formula by pasting another formula, at the beginning or the end of one formula, I must be very careful that the cursor is inside the formula to be extended, else the two formulas will appear as two separate formulas (which structurally is not nice, and it prevents to select and copy the entire formula, as it is not one formula, but two of them)

Last thing : it looks more like a (tiny) bug than a design decision : when I want to enter this kind of integral :

then the Ctrl-F shortcut for the upper bound will be ignored once, which is not the case for the lower bound. The same is true for the square root shortcut Ctrl-S and the same behaviour applies to the discrete sum.

Regards,

Pierre-Henri