I feel it's more of people that play nowadays don't want to take the time to "apply" to a clan they are not certain to get in. So they'd rather just be tested in-game and see if they get a yes or no, rather than wait ~a day-week. So really it depends on the person, if the person is the type (such as yourself, Fame) that prefers the application system, they put up an application and wait the time to see their designated fate within that clan, however if they are the type that prefers a quick-and-easy system such as a system defined by testing the player in game and that test results in their answer of yes/no, then they'd rather do that.
Another thing is as Hikou said a 'good application' is purely subjective. Not only on the applicant but the clan itself. For example my clan currently, we have no designated "format" or "information" required other than the applicants GMT, while as some other clans have a certain format or required information, a app that looks good to us (Solus), could look horrible to another clan.
Last point is that the only way to truly re-vamp the recruitment system is to well, force people to apply instead of doing tests, however that won't exactly work because each person has their own prefrences, some clans do both ways, some do one way only, same for applicants.
TLDR: Revamping the recruitment system is a very gray area bc of the subjectiveness.