At 1000 gp per summoning for objects that weigh only 10 pounds, can't be done if someone else has the object, requires preparation and an object that will likely be taken off you with the rest of your gear. It sounds good, but the restrictions make it hard to get any mileage from.
Not at all. You seem to be viewing it as a spell that summons some item you need while imprisoned (hence your comment about being taken off with the rest of the gear). That is not what the spell is for. It is a great spell for stealing items (like rare books from a library). It also is great for planting items on creatures and tracking them. It is also good for smuggling items like weapons or magic items into situations where both are prohibited and screened for. All of these are specific uses of the spell contemplated by the spell. Add to that the ability to deliver valuable and possibly sought for items without risking theft, and while the spell is situational, it is also fully functional and usable as written.
You throw 6th level spells and this thing produces minor distractions. It doesn't cut the mustard without you taking further measures that make use of it.
Minor distractions? It is meant to ward your stronghold from assault. A 50% chance at EACH intersection to take the wrong way? That's worth the spell on its own! Think about an enemy army trying to assault your stronghold with this thing going. With the suggestion ability and some nice mechanical traps placed at choice spots this spell can make a stronghold a death trap, especially to normal troops.
Programmed illusion does nothing that lower level illusions can't, except trigger automatically. Finding a scenario where you use it and not another spell is non trivial.
Except when it is used to leave a detailed message (including, perhaps, visual directions and a map) to friends, or drive people invading your stronghold into a pit trap. The trigger automatically is the selling point of this spell and it's pretty huge. Are you going to use it in the middle of a fight? No. But is it an awesome spell outside of combat? Yep. As a DM I have used it plenty against the PCs.
Again, what is the situation where it does something you need? When you have an army that need to get past something impassable. Typically a fair bit of work to arrive at that point.
Not counting the various uses of this spell offensively to shoot or divert an object through it for what basically amounts to indirect fire (like diverting a river into a dungeon or lava or flaming oil), this spell is quite useful for moving not necessarily armies (though it has that usage) but groups of creatures larger than teleport or dimension door can handle. Beyond that, its duration allows for a raid into an enemy dungeon or stronghold and then a retreat avenue out of it which, since it is concentration, can be dismissed so that the enemy cannot follow. Arcane Gate is almost certainly the ultimate commando raid spell.
The spells I listed give niche bonuses for their precious 6th level slot. Find the path has situations where it is useful I'll, and those situations are where you want to get back to somewhere. Like the spells I listed, you probably won't even prepare it unless you need to do what it lets you do. Making it the ultimate bad guy lair finder is not conducive to a fun game.
The spells you listed have specific functions that make them useful in a variety of situations. They might not be useful in the middle of combat by a 4 man PC team running through Rise of Tiamat, but they are very useful spells in campaign situations where PCs have strongholds or are engaged in more than 4 PC dungeon runs.