Second Son is not 10 hours long. Sure one can make it such if they just lounge around doing nothing but if you are going through the story, its probably closer to 5-6 hous. Unless someone is counting all the repetitive side stuff to 100% each district, the average person will complete it long before 10 hours
And game prices aren't based on length and they shouldn't be. Each game has a budget and money made needs to exceed the amount it cost to make the game. Even at $60, some games still lose money bc game prices have not gone up to account for the changing economy from the past 7-8 years. Minimum wage has gone up, development costs have gone up, production costs have gone up, distribution costs have gone up; and game prices have stayed the same. And because of all that a lot of mid-tier publishers have shut down.
I don't pay $60 for games (bc they tend to drop fast anyway), but that's a fair price when one takes into consideration what it takes to actually put one out. $60 as a standard may not be perfect but it works out as the market to adjust that based on spending practices and other factors. You'll see retailers run sales or even the publisher slash the MSRP much sooner now than ever before in the past. $60 is only for those who are completely impatient. Most games can be found for $10-20 less within the first month somewhere