Care to share which comboes irk thee so?
None of the following would be allowed in my game, no matter how much you begged:
Zhentarim Fighter variant class
Imperious Command
Doomspeak
Never Outnumbered Skill Trick
Dreadful Wrath
Dread Witch PrC
Nightmare Spinner PrC
Shadowcraft Illusionist PrC
I just love how melee types get an option to deny an opponent actions via, for example, Intimidating Rage, Instantaneous Rage, Imperious Command, and the Never Outnumbered skill trick.
...at will, through spell resistance, and at DC's that depend on skill bonuses (the optimized build in the handbook you link to averages about a 54 DC Will Save to resist, and includes suggestions for getting the average DC up to 73 or so).
It's too easy using the full range of splatbooks for casters to bump the DC's of spells up, but if you allow spell like abilities save DC's to depends on skill bonuses then it even more strongly encourages the all or nothing immunity based game you see at high levels.
Such a thing is normally the domain of casters, and seeing melee get a shiny BC option is cool.
Seeing melee get some battle control/buffing/debuffing is cool. Silly tricks like the above is not. Basically, I believe that casters are too powerful and have too powerful options that make them even more powerful. So, since I intend to take casters down a peg or two, I don't feel the need to make BC/buff/debuff options for noncasters compete in power with what is possible for casters via WotC's endless poorly thought out source books.
Equally as bad to me as the lack of balance is the shear ugliness of the WotC 'system'. Some of the powers are class abilities. Some are feats. Some are skill tricks! Some interface with the skill system: others create new subsystems of their own. Some are extraordinary abilities: others are supernatural. Often there are six or ten mechanical variants on the same concept. It's a mess, and to a large extent its that mess that creates all the unintended consequences when you start pulling things from disparate source books.
I personally feel the start of making it viable is making the skill itself actually useful even without any tricks, classes, and feats. I'd remove the restriction of needing to be threatening the target in order to use demoralize foes and just allow anyone to attempt to intimidate anyone within 30' who can clearly percieve them. Then I'd allow you to trade penalities on your skill check for improvements to the effect like additional targets, all targets within range, greater range, additional penalties (-3 rather than -2), etc. with no need for feats or skill tricks. This makes the skill and the action valuable in and of itself.
Then I'd add feats that made it better. Some ideas off the top of my head.
Feat #1: When you demoralize a foe, you can also attempt to intimidate every foe you threaten for free.
Feat #2: Whenever you demoralize a foe, the shaken condition always lasts one round longer than normal.
Feat #3: Whenever you rage, you can demoralize foes as a free action.
Feat #4: Whenever you charge, you can attempt to demoralize the target of your charge as a free action.
Feat #5: Whenever you score a critical hit, you can attempt to demoralize foes as a free action.
Feat #6: Whenever you drop a foe (ei, render them dead or unconscious), you can attempt to demoralize foes as a free action.
Feat #7: You can trade your normal full attack action for a single attack + demoralize foes.
I'd consider bundling Feats #4, #5, and #6 into a single Tactical feat. Note that the system is unified and largely classless. There is no need for PrC's, variant class features, skill tricks and all that other baggage. It's clean. Every single thing channels through the skill system, and because the skill itself scales there is no need to describe how anything else scales. At low levels, you do a 'Finishing Move' and kill a foe and you can try to indimidate his friend at the same time. At high levels, you do the same thing, and you can try to intimidate ALL of his friends at the same time and its just built into the system.