It seems a majority of the discussion here offers evaluations that are very accurate-
(and)- mostly centered on "now". Things change folks! You change, your city changes, the game changes...
I was going to Lay out some examples here.. but.... they seem too long.
So, just saying... there are times/places where using even "Weak" Mortars will make a huge difference.
And, in chapters right before Frog Upgrade, they can be a Primary Unit- or especially useful in "terrain Restricted" situations.
Upgrading Your Toad can make a huge Difference...
After Final Frog Upgrade, FROGS will often be your primary unit- But still, sometimes include a Mortar, because it is stronger, and will "-attack bonus" on an enemy.. (and mortars are better vs archers).
Orc Strats are Simply KILLER, vs a single Archer... they have Downside in any other application; They walk out and take hits from all enemies, They Cant bomb enemy targets before they move... they are Expensive to build... (I'll rarely use more than 1-2 at a time, mostly when enemy has a1-2 archers, and at least one of them must die on first turn).
Strengths.. weaknesses... enemies.. tactics.. Things Evolve!!
Way-back, i upgraded BULWARK, just to Stockpile "useless" barbarians.
Now, getting around to getting them some bonus with Vic Springs....
And, I see a payoff coming... =Where i Can dip into Barbarian Inventory to save my "better" units...
Similar with Mortars... for a While, they bore a Heavy Load.. now, finding places where they save me some frogs/others...
I guess.. just saying,
Try to not just look at "Where you are"..... but also look at "where you are"..... ?