For example, is it possible to have LEGO like slot fitted bricks, with cavities in slots filled with mortar?
Alternatively, toothed bricks that can be slotted, such that the top brick slots into two lower bricks.
But it would make the "hard" part of laying bricks (on wall connections which might not be right angle, when you only need 1/5th of a brick to reach the wall/window/door opening...) even harder. Basically, you'd move the mortar laying complexity into "where and how do we join the joints".
Basically, how many non-right angles did you make with regular Lego bricks? And how many types of Lego bricks did you need to get that nice figure built out? :)
Here is a great video (and a great channel generally) on the subject: https://youtu.be/MRipzKkeQik