Having enough information to make a decision is important. Companies are selling all types of information management systems out there that have pages and pages of fields that get you all the right information! Right? Wrong! Such systems are bulky and lose as many candidates as they catch. No one wants to spend 6 hours filling out a form for a job they may not even have a chance to obtain!
Sure it separates the really motivated people from the not so motivated. Not really either. People who are busy and have a good sense of time and effort don't want to fill out forms and waste time. They want to apply within a reasonable time and move on.
A better way to manage such systems is to upload a cover page and resume and let the system do the work. There are plenty of excellent resume scanning software out there. There are also plenty of ways to obtain access to Linked-in and online profiles that save time and money.
No need to fill out those forms! Long forms are useless. Employers should seek enough information to make a decision to seek additional information. It is not necessary to hire the person in the first round. It is much better to use the time to build a little report with the candidates through information requests and discussions.