In the 1950s, a ketchup company changed the lid to be wider, easier access to ketchup. They went bankrupt.
People hate change. Giving no option but change people will leave. Giving them back their customary page is a better idea even if you label it classic view.
Your running this outfit with someone without experience. That is the only explanation for the sudden change. They are probably college-educated, brilliant students, with no practical experience in the world of business. At least that is what the new appearance shows me.
Microsoft also did it with Windows 10 which happens to be very unpopular with a lot of people.
Those that do not learn from history are doomed to repeat it.
David J Webb commented
You have to have experienced people with a background in national psychology and hidden persuaders. If that is not the case, you will pay for their lack of experience in everyday customer relations. Leaving people no choice means they vote with their wallets. This change will take time but it will leave this company bankrupt if you are not very careful.