I am sorry if it felt like I did not read the question thoroughly.
I have done some research for you now which will hopefully provide the full answer to your questions below:
1) I am wondering why the pagination in i.e. the ListView can't be focused (tabindex -1 is set).
This is done on purpose to prevent navigation from continuing to the pager.
2) Is there a special reason for this construction?
The reason is so that the user can "leave" the Kendo UI Grid/ListView etc. without having to go through each page anchor.
The negative tabindex was implemented in the Kendo UI Pager for R3 in 2012. In case you wish to patch it, you need to target adding the attribute in the update function
(tabindex=-1) and the template