Full prepayment isn't a mandatory trend, but it's definitely a widespread practice. Hotels have indeed started requiring it more often because it protects them from cancellations and no-shows. This especially applies to popular destinations and peak seasons, when rooms sell out quickly. But it still remains a specific hotel's policy rather than a universal standard.
Check exactly what's stated during booking: on Booking there should be clear information about payment terms. Sometimes when you choose a certain rate (usually a cheaper one) they require 100% upfront payment, while other room options allow you to pay a deposit instead. If you don't like the conditions, you can always look for alternatives - plenty of hotels stick to more flexible schemes.
Also pay attention to the cancellation policy. With full prepayment, they often limit your ability to get a refund without penalties or set very strict cancellation deadlines. Before you pay, read carefully until what date you can cancel the booking without losing money. If it's a five-star hotel with a good reputation, the risk is lower, but it's still worth playing it safe.