Because it is a spacer vs a new shock and coil.
Suspension feel is subjective. Some people think the stock suspension is too soft, and therefore like a new setup with a stiffer coil (RC in this case) and some prefer the feel of the stock suspension, and therefore a spacer is better in their opinion. Its just like the debate on spacers vs Bilsteins on the regular F150s. Many people swear by the Bilsteins, and some put them on and take them right back off becuase they ride different.
Personally, I like the feel of the stock suspension (I wont be taking my truck off road much), so I plan to do a spacer, plus I am just not a fan of RC overall, but that all relates to my experiences with them in the Jeep world. I am sure they have made improvements since I swore them off as a cheap (price and quality) brand.
And as stated above, tires will make a big difference in how stiff the ride feels. It is hard to find a good tire above 34" in size that is not a 10 ply E tire, and those will always ride stiffer than a LT tire.
One thing we can all agree on though is that the amount of rake from the factory is ridiculous and needs to be addressed in some manner.