Wing Woo Gar
Senior Master
Taking the space or balance is as gratifying as any successful strike IMO.Inside upper body block can permit the attacker to drop the elbow of the blocked arm straight down on the defender's chest if they're trained well enough. But I don't expect people to do that typically.
Defense is to block the attackers arm between their elbow and shoulder. This should also open their armpit nerve cluster to attack, among other fun things, perhaps osoto gari. The risk of an inside block is more commonly the attackers other hand of course.
One of our principles is "A person's unbalance is the same as a weight." Stealing their balance is one of life's pleasures. Grab, pull, push, trip, throw, etc.