The reason of asking Initials might be being professional and responsive. Like while creating the email IDs in organization for official ID, they use initials to make your ID. Like John Keates might have email ID as JK@ abc.com.
They might be asking for desired initials, because in our organization I saw few people who randomly got initials in their IDs or User account for web based financial software, were funny and hilarious. like Sabir Ali got the ID SALI, which if pronounced in local language (Pakistan, India) will mean sister in law. similarly another fellow Zulfiqar Alam got ID as ZALAM, whoch pronounce as a word in Urdu/ Hindi which means cruel.
I might be wrong but if the intention is to preempt the situations as stated above, would be great idea.