justified in being irritated by composer install for CI4?

vendor/codeigniter4/framework/app is there in case there have been changes in the app folder that you need to incorporate into your app folder. These are pointed out in the release notes for a version. This approach doesn't clobber anything of yours, and provides a reference for an "unadulterated" app folder. I would not say this is not useful.

if there is a reason, thats fair enough . 

So to summarize
1) i don't need to add something like 

Code:

require_once('vendor/autoload.php');

to bootstrap index.php file , because  everythig i need is auto loaded for me already.

2) I can basically ignore app in vendor ; if it confuses me ( i do like to poke around code) I could take out app and put it on my desktop as a reference

just had a look at up in /var/www/htdocs/CI , all my other additional stuff like bootstrap4, gulp dependencies like

Code:

"gulp-concat": "^2.6.1",

etc is listed and taken care of via package,json