spread axles have been used on large commercial trailers for years with little or no problem. In the commercial world it is usually a weight issue that spread axles are used.
When a travel trailer gets lighter due to design there is no need to use a spread axle set up for weight purposes.
However having the axles spread apart by a given distance does increase the trailers stability and tracking as it travels down the road. Think if it in terms of a car...a car with a short wheel base will handle much differently than one with a very long wheelbase. The longer the wheel base the less impact expansion joints have, the better the ride quality and the more stability there is going over sudden road problems.
The small car short wheelbase will often jerk around and be generally squirrely over many road conditions.
Now the car manufacturers have learned how to damp all this out with excellent suspension systems and by putting small car axles at the extreme ends of the car.
The same happens to your travel trailer.
My guess is this move by the manufacturers is to avert the ever growing demand for REAL suspension systems for trailers including adding Shocks and possibly disc brakes at the factory.