I respectfully disagree with you Walkure. I would argue that with the BFME1-style fixed build system, we are more, not less focused on sieging than in aoe2. Simply put, sieging HAS to occur in this game, to get through a castle (granted, mordor and isen are the exception) whereas many games in aoe2 can end without a siege, without siege weapons because of its free build system.
It's not that BFME1 is more or less focused on siege than Age of Empires; my point is actually that Age of Empires is on a totally different league than the BFME universe, whether it be the first or second chapter.
As you've fairly pointed out, the next patch will bring a new breath of fresh air in its attempt to revolutionise siege and spells altogether, thus avoiding more and more the risk of the famous/infamous pre-determined games. Notwithstanding that this shall happen and be a remarkable feat for the Mod, I still believe that this founding premise does not really detract from the fact that Age of Empires is governed by different laws and another general logic.
In previous words of mine, this iconic RTS series is the quintessential epitome of skirmishes, embodied by a basically endless succession of advance/retreat clashes, which is what mediaeval and modern tactics exactly consisted of (aiming to conquer specific objectives to use later as a persuading lever against the enemy), made even more fluid by the canonical free-building system; nevertheless, while we don't have a real central and vital point to defend here (like fixed fortresses or camps), lest we be destined to perish, the game itself offers a vast variety of siege weapons and options which goes simply beyond imagination, ranging from ballistae or trebuchets to mobile cannons or cannon-armed vessels. Tonnes of siege possibilities, as many as what you dispose of in terms of traditional troops.
Therefore, in such aforementioned context, it's not that siege occupies a more or less relevant spot in every possible strategic plan; it's rather that siege itself runs in the game's veins as one of its integral and pervasive souls, whether games end with siege or not (with the latter eventuality being quite rare, by the way). To put it in a briefer manner: think about siege weapons as you would think about standard infantry, cavalry or archery. This is what I'm trying to say.
Said that, I would then argue that BFME's specific case presents a stark difference, in that siege weapons are rightly confined in a more contained dimension, where the entire concept of siege is structured to serve more defined purposes; and, without a doubt, if it's true that siege weapons don't fulfil a mere supportive function, they're not granted the same level of prominence as normal units nonetheless. And it's a good thing that the logic behind differs, because BFME favours major decisive battles instead (following, now, in the footsteps of ancient warfare).
So, I do believe that stationary trebuchets would not suit the Edain Mod, since they fare well in Age of Empires, but wouldn't likewise in BFME: major battles would not allow their full potential to be used effectively, the whole battle scenario is not enough spread throughout the map to give them a proper margin of action, the very weapons would be left at the mercy of cavalry (far more versatile and faster than that of Age of Empires) and so rendered useless. Not to mention, as I've written in my previous reply, that, in order to give such kind of static (when assembled) trebuchets a fair advantage and differentiation, range and damage would necessarily have to be increased (with the risk of frustrating any wish to counter overpowered catapults).
My overall thoughts and personal impressions, of course.