Well, Rakudai definitely has spent more time establishing characters because they spent the first two eps on them. Asterisk developed Julis in Ep 3 and 4. We've gotten bits and pieces of Ayato as well. It's just Ayato isn't nearly as compelling on that front because there are a ton of questions still.
Ikki is pretty straightforward and easy to understand in regards to background. Also his background makes you want to cheer for him. Getting looked down by your own family and the school? Prove the wrong!
Well, Claudia has been the main source of that in Asterisk and it's been rather tasteful, all things considered. Rakudai though, we had that riding on top of Ikki + blushing, the wash your back scene in Ep 2, stripping in the mall in ep 3, and then the shower scene at the start of 4. That's way more than Asterisk.
Then there's the creeeeeeepy sister. Ugh.