That's not true. When Shimano sells it's 105 radially laced front wheel, are you saying the hub in not warrantied? Many manufacturers sell front radially laced wheels. All Phil Wood hubs are warrantied for radially lacing.

If you radially laced older hubs that were not designed to handle radially lacing, it did void the warranty. But, nowadays hubs are designed for radially lacing.

There is nothing wrong with radially laced front wheels, unless the hub isn't designed for it. The front wheel does not have the torsional load that the rear wheel encounters, unless you have disk or hub brakes.

As for the harsh ride, I believe this in nonsense. Read Sheldon's (pbuh) article about this. If you can feel the difference, I am amazed.