why do there need to be fees for like passphrase setup. of course for transactions but others why. who gets those fees
From the networks point of view a transaction is a transaction. Doesn't matter if delegate registration, sending Lisk or setting up second passhprase.
Fees are needed to avoid spam.
If any transaction is free on the blockchain it can used to attack it, slow it down, bloat the blockchain by creating hundreds or thousands of transactions every minute.
If there is a few an attacker can still do it, but it would cost him. The ideal fee sturcture is one that is cheap enough for legitime use, but too costly to spam the chain.
It's to discourage locking up addresses. As Lisk is a brainwallet, if there were no fees for a second passphrase, anyone could create a botnet and lock addresses. By having a fee in place, this is negated.