The problem is that hammer forged barrels (the cheapest, most common, and most flawed way of making a barrel) leaves all kinds of internal stresses in the barrel which cause 2 things- bad harmonics and uneven metal expansion/warping as the barrel heats up. Pressure bedding the front of the barrel dampnes the harmonics somewhat and prestresses the barrel and directs its expansion as it heats up. With a good barrel that has cut or button rifling or better yet, has been stresse relieved through cryo treatment, you absolutely want the barrel to be free floated. Since most factory rifles are made as cheaply as possible, they are pressure bedded by default. Its worthwhile to try to freefloat them, but there is a chance that this will hurt accuracy.
If hammer forging is done correctly and the mandrels are thrown away when they are supposed to they make a beautiful barrel. Unfortunately some major manufacturers choose to use the mandrels longer then necessary since they are very expensive to make. Just so you know Sakos,Tikkas and Browning Abolts,Steyrs are completely free floated as well as Hammer Forged and I dare you to find a gun that can match them in accuracy or a barrel that is as well made with exception of a very good custom barrel. Remingtons on the other hand are button rifled and need a pressure point on their barrels to really shoot their best that has been the case with everyone I have owned unless rebarrelled. Savages have button rifled barrels but the bores I have seen are very rough and they are stress relieved by hand. With Quality barrels(Lilja,krieger,hart,shilen,pacnor) costing in the 200-300 dollar range these days how can a manufacture afford that and sell the gun for a profit? BTW that list of custom makers includes Button and Cut rifled . One could start a pissing match comparing the benchrest results of Krieger vs Hart vs Shilen vs Pacnor ad nauseam ad nauseam . Winchester barrels are hammer forged some have pressure applied to the barrel and some don't, they have extremely inconsistent barrel quality and have given me fits trying to shoot them well, some of the worst shooting guns I have seen in quite some time, for that reason I dont buy them anymore . Some actions flex more then others and therefore not good candidates for free floating. Every barrel has stress in it except a cut rifled barrel and even those from expensive barrel makers do not guarantee an absolutely smooth bore or tremendous accuracy. Now if you want to talk generalities thin barrels are better bedded and varmint barrels are better free floated but there are exceptions in every case.