Hotels are banning tiny plastic toiletries. Environmental experts think they can do more.

The hotel bathroom is a cave of wonders for kleptomaniacs.

The jackpot, as eager hoarders know, is the assemblage of tiny toiletries — delicately placed atop the granite sink to be used once, then thoughtlessly shoved into vanity bags for the rest of eternity. But for these teensy plastic bottles (smaller than the TSA-mandated 3.4 ounces for carry-on liquids), the end times are devastatingly near: Marriott, the world's largest hotel chain, and Intercontinental Hotel Group, which owns a dozen hospitality brands including Holiday Inn and Hotel Indigo, are the latest to replace their tiny toiletries with dispensers or larger bottles.

Large hotel chains are slow-moving and take time to enact change on all their properties, says Willy Legrand, a German professor of hospitality management who does research on sustainability at the International University of Applied Sciences at Bad Honnef. "At the end of the day, they're businesses trying to run as efficiently as possible," he says.

Right now, it's beneficial to turn their attention to plastic with the recent bans on plastic straws and single-use utensils in restaurants, but environmental activists are highly critical of symbolic, feel-good initiatives.

In an op-ed for MarketWatch, Massachusetts Institute of Technology professor Yossi Sheffi writes that the tiny toiletry ban seems like "more of a PR exercise than a real attempt to move the needle." The author of Balancing Green, a book on corporate sustainability, Sheffi argues that hotels must factor in the entire supply chain when considering a product's environmental impact.

The goal should be holistic sustainability: reducing waste and energy in all areas of the hotel's operations. For example, Marriott also focuses on landfill and food waste reduction in addition to plastic, Naguib adds. Since Marriott owns more than 7,000 properties, implementing the amenities change can take months. Any bigger, large-scale change, such as retrofitting a building to be more energy efficient, can take years and requires the approval of multiple parties, says Legrand.