In weakness lies opportunity
Like most here, I would agree this is a great opportunity. Most of all, it's a great chance for hillarity. The best moments come when players are forced to improvise some inconvenient ways to get out of a situation. If everyone fills a different niche, it quickly becomes this anime/cartoon episode where everyone pitches in with their one unique ability to save the world with the power of friendship!... but that kind of negates any drama that could potentially be built.
When I DM, I actually create situations where I have no idea of how the party is going to solve them. But they're 3-6 players with their own insights into the party and their own character; let them figure it out. As a DM, it then falls to you to allow or disallow certain ideas they come up with, depending on how reasonable they are and to sometimes think of a DC for them to clear. If you're worried that the party will struggle at certain points, you can have backup solutions etc.
Say your party is unlikely to clear the STR-DC check.
- have a secret door hidden away somewhere, to be found with perception and investigation.
- guards that can be fooled
- provisions or loot coming into a place, allowing the players to hide in the crates
- a riddle or puzzle to go around the obstacle (secret paths, ...)
- enlisting the help of NPC's (a particularly stupid but gentle ogre that will lift the gatehouse for the party in exchange for his favourite food,...)
I usually prepare for a "brute force" way and a stealthy-puzzle-deception-filled way. (Though not always obviously).
As an example from personal experience:
One of the first adventures I DM'd, the party had to interrupt a ritual being cast by a mysterious Serpentine Cult. The party consisted of 3 lvl 1 or 2 casters; Gnome Warlock, Elladrin Wizard and Wood Elf Druid. They realized their low AC and HP could mean trouble against overwhelming numbers. So they strategized. They searched for, and found hooded cloaks worn by the cult, lowering the deception and persuasion DC's. I threw them an additional curveball by saying there were no robes in the Gnome's size. They could have taken a robe and "cut it to size"... but no... the Gnome decided to hide under the female Wood Elf's robes and had to match her steps and follow her lead. It was good fun with jokes going all around the table.
They then went along with the ritual, trying to save the captive person from being sacrificed. In this case, it became possible for them to see and hear from up close what was happening here and what the cult was trying to achieve. They heard and learned some of their close-guarded secrets and learned the true name of their enemy.
They moved through the crowd until they were just in the right position to unleash their AOE (Thunderwaves if I recall correctly...). Their position, the surprise I had the cultists undergo, the panic I simulated, all circumvented their lack of HP and AC. Having blown the crowd of potential enemies all across the room, they ended up in a very short caster-battle with the cult master, whom they promptly blew into such tiny pieces, they'd fit in a rather small matchbox.
If they would have had their monk and barbarian friends there (who were absent for that session), they would just have stormed the room, engaged in an all-out battle and none of this interaction might have taken place. They wouldn't have known who these cultists were or what they were trying to achieve.
So if anything, a certain "weakness" or "vacuum" in your party's skill-and-stat blocks opens the door to some very interesting and inspired encounters, as well as possibly give you opportunites for certain relevant exposition and plot-reveals.