As the title says, the fee for opening a new account on MPEx is 30 BTC, effective immediately. Already existing accounts are unaffected. The fee is projected to keep increasing for the indeterminate future.
How do you justify this ridiculous fee? where/to whom does this fee go?
That's not how it works. You have to justify to yourself that it's worth the fee.
If they haven't communicated value, then they've failed at marketing.
Different things. They don't owe you anything, so they don't have to justify anything.