FoK does better in how good the game looks, true, and also has better balance, but TTRU is closer to table-top in many ways, like unit scales, the quick reinforcement out of battle (sort of like buying them beforehand in table-top) and most of all the ranges and weapon damages. A single lascannon shot will kill most infantrymen in one hit in tabletop, and it's the same for TTRU, but not in vanilla DoW or FoK.
The damage is worked out via formulas that are true for table top, as are units HP and Regen relating to a units Toughness and number of wounds, along with special abilities such as Feel No Pain and Eternal Warrior.
Game Balance, mainly the reason. Still, throw 3 Triple Lascannon Predators in front of anything without an Invulnerable Save, and you're looking at complete wipeout of most enemy infantry hordes.
When you say balance, it's only as balanced as you're willing to play.
For example, if you say play 10 minutes, and then measure the armies, you'll see Marines will have far less than opponents, while the Guard will have more. However, play it until you have full slots, and there will be absolutely no balance - The Guard will only have so many platoons, yet there are 60 Marines with Bolters firing at T3/AS5+ creatures. Not that good for a guardsman, considering the Marines 'outpoint' them by about double.