That's how the Sniper update was too. The Huntsman doesn't have as long of a reload time (that I can tell at least) (and also doesn't have the scope, though that's seemingly compensated by being more forgiving in regards to headshots compared to unscoped rifle), allowing for quicker firing when it's necessary on offense (and defense), and Jarate made it more of a team-player (unlike on 2Fort a lot of the time, where Snipers will just kill other Snipers, ignoring the needs of their team), making Sniper more useful when it comes to team charges.
They also wanted to give other players more of a chance to spot, dodge and counterattack snipers. They provided incentives for snipers to get closer, including the advantage being able to charge your shots without a fisheye scope gives against spies and scouts at close range.
Stickies, like long-ranged headshots, often don't give other players much chance to respond. The only way to make sure you don't get insta-gibbed by a bunch of stickies around the corner is to make a target out of yourself by carefully checking every doorway. The shield provides incentives to charge at the enemy instead of camping around a corner.
Or it could be the other way around and during testing demoman would plant a bunch of stickies and stand at a distance waiting with the shield out to protect themselves from flares and rockets.
Also, would soldiers with that new rocketlauncher have more trouble taking out scouts?