Things change
If things change in your life like mine (kids get older-want bigger toys-wife wants more comfort/room) you will want that extra capacity. It started out with a utility trailer for motorcycles and morphed to a +7500# toybox and I am thankful I ponyed up a few hundred dollars, it was a bargain. Saved me the hassle and $ changing trucks. What if you want get a bigger boat or travel trailer, maybe a toybox (very heavy), your options will be limited and you do not ever want to tow at the limit unless you tow on dead flat terrain and have zero wind.