Debug Toolkit makes debugging your code easier and more enjoyable.
Why it is recommended?
WordPress MVC (WPMVC) framework provides debugging functionality through its logging system, which creates log files.
This system is excellent when trying to debug the code on live environments because it let you inject debugging calls without affecting the execution of WordPress; the cons is that the output needs to be read from the file, which will need to be accessed through the server (via FTP or other file managers), making it not ideal for development environments.
Debug Toolkit, on the other hand, will let you inject debugging breakpoints that will output in HTML, making development much easier.
vdump_and_die(). The first can be used without stopping the execution of WordPress and the second will stop immediately.
This makes debugging during development much easier.