Not at all. Agents are the way to go if you can afford it. Close friend used an agent in Pattaya 2 days ago to obtain a bank account, change visa from TRV to Non-O based on retirement and did't need to deposit the funds in his bank account.
He lives in Bangkok, was picked up at Pattaya bus station by agent, taken to bank to open bank account, 30 mins at bank then on to Immigration. Very long line waiting, that was bypassed by agent, straight up to desk, sign the papers, photo taken left in 15 mins. Visa will be ready in 2 weeks.
He has plenty of funds but is not prepared to tie it up in a very low interest bearing account with only 50% available to use for 7 months of the year.
So agents are well worth it if you can afford it to save a lot of time and all the associated problems dealing with Immigration and their constantly changing interpretation of the rules for visas and the stress it causes a lot of people