How does it sacrifice precision of movement? In fact, most (inferior) turn-based systems restrict themselves to squares or hexes (luckily not Divinity), and those clearly do restrict both precision and choice.
Units in RTwP have less precise methods of movement because, first, they move without restrictions in a 2D plane (but are still subject to pathing around that terrain) and second, the amount that these units can move in, say, ten seconds is difficult to define. Because there is no method to determine a unit's exact movement range with respect to the terrain in a given time, it is impossible for RTwP movement to be as precise as turn-based movement. This is because turn-based movement is always restricted to some measured form (e.g. a unit with 5 tile movement range will be able to move exactly that much in a turn, barring status effects) and this makes it inherently more defined and strategic than the less-defined, real-time movement.
This same logic can be applied to line of sight and ability/attack range between the two systems.
While there are less direct movements a single unit can make in a turn-based system, there is the possibility of much finer control over the movements available - which, in turn, allows for far more intricate strategies to be pulled off. It is essentially a sacrifice of
some individual unit freedoms for greater control and coordination over your entire command of units.
I'd argue that any luck-based system is inherently nonstrategic. Is Go luck-based? Chess? Starcraft?
Statistical chance is at best an abstraction you use if you have no other choice.
Let's take a step back and remember you're championing a real-time implementation of the D20 system - an
entirely dice-rolled game.
But, anyways, these systems aren't luck-based so much as they are a test of the player's strategy. There are many ways to mitigate the RNG, and the constant threat of failure demands that a player always have a back-up plan or failsafe
For example, I've lost a game of Fire Emblem because an enemy managed to roll within his 3% chance to critically hit, instantly killing my commander - but that mistake was mine. I should not have put such a critical unit in a situation where that could happen - it was a tactical error on my part.
XCOM is built entirely upon imminent failure (aka random chance). Especially early on, your units will miss often and die constantly. The game itself is
entirely about mitigating and minimizing any potential for disaster; you as a commander must have a back-up plan for your back-up plan as well as a worst-case scenario escape plan at all times, or else your RNG-failures are your own. Success is won through shrewd, tactical risks and sacrifices, and lost through ill-planned rolls of the dice.
Lastly, I would say that statistical chance is a necessary aspect of any level-based RPG. It is an abstraction necessary to maintain the illusion of power between units of differing levels. While it can be frustrating, it is the best way to represent the unpredictable nature of existence while at the same time respecting the fact that it is a game.