...not quite that simple!
Unfortunately, it is far, far, far more complicated than that! Forward lean--which is influenced by boot cuff alignment, boot design and fit, footbed design, internal ramp angle and heel lifts, external ramp angle (boot sole angle), delta angle (the effect of bindings), leg and calf shape, and ankle range of motion--affects ankle and foot function, fore-aft balance, range of flexion-extension, and the ability to tip and steer skis. While there is some room for personal preference, optimizing fore-aft boot setup is absolutely critical if you want to perform your best.
And there is no substitute here for a top-tier bootfitter who can decipher all the variables I mentioned above and come up with the best individual solution specifically for you. Unfortunately, very few skiers will probably want to invest the time and money required for a truly customized setup with a skilled bootfitter. But without it, your skiing will at best be marked by compensation for sub-optimal setup, which willl handicap your movements and limit your performance.
That said, you can exert forward leverage on your skis (if you need to--another discussion!) with even a poor fore-aft setup. It's not whether you can do it--it's how awkwardly and inefficiently you have to move to compensate for your setup. Perhaps the biggest effect is your ability to balance fore-aft through only a limited range of flexion-extension (short-tall). I've posted this diagram before, but here's a simplified look at this effect:
The first column shows a skier with A1) optimal setup, B1) boots too upright, and C1) too much forward lean. All three skiers are balanced over the middle of their feet (note the dotted line through their center of mass), but skiers B1 and C1 must adopt less-than-functional stances to compensate for their boot setup. The second and third columns show how skier B cannot flex deeply without falling over backward (B3), while skier C cannot extend fully without falling foward (C2). Only skier A can flex and extend through his full range without losing balance.
Of course, none of this matters much if your boots don't fit snugly, or if they are very soft. But stiff, snug, high-performance boots are worse than useless if they are not set up properly.
But again, this illustration shows only one aspect of fore-aft alignment. Boots must also adapt and compensate for optimal foot and ankle function. Many skiers lack sufficient range of ankle flexion ("dorsiflexion") to even fit into a boot with a lot of forward lean, and attempting to do so can cause excessive pronation (collapsing arch), which affects edging movements and knee function, not to mention pain and foot problems.
I'm not trying to scare anyone away from this topic. But I'd love to convince everyone to find a good bootfitter. Your skiing will thank you!