Can you bypass the listing agent?
ABSOLUTELY NOT
It's easier to deal with a thousand agents across the country (whose paycheck is partially based on how nice he/she is to the asset manager), than it is to deal with 500,000 buyers complaining about how long it takes to get a response to their offer. Also, banks don't have the time to deal with the thousands of incorrect/incomplete offers that are submitted each day.
It's important to note that the duties of an REO listing agent go far beyond those of your average agent. Just ask anyone that's had to help with evictions on a few crack houses; Or having to visit a property once a week and make maintenance and utility payments for 4 months before ever listing the property.
When you make your offer directly to the bank or asset manager, that offer is sent back to the listing agent; in some cases (very few), this act can cause the agent to be looked upon in a poor light. If warranted, so be it. But if not warranted, you're only going to make the agent look upon you in a poor light. If the agent just isn't giving you the personal service that you would like, welcome to REO - consider taking 4rmgt's advice.
On a related note...
Banks CAN sell without an agent. Remember, Federal law doesn't permit them to BROKER sales, but just like any other property owner, they're afforded the legal right to sell their own property without a license. Of course very very few do this, as it's very tough to sell for a reasonable price on the open market without a pair of eyes and ears on the ground. It's more common in the commercial arena, and with smaller localized banks.