“The difficulty is we need” vs. “The difficulty is ᴛʜᴀᴛ we need”

Solution 1:

The issue here is that we're using a fully independent clause as a direct object. Let's try something really short on for size. "Your problem is you think too much." This seems to survive fine without the that.

If we invert it—"You think too much is your problem"—Well, then first of all we discover that inverting it ill-advised, but sometimes it helps us get a handle on what's going on. In this case, adding that would seem to help pull the clause together into one entity: "That you think too much is your problem." That's still a bizarre syntax, but the "that" seems to have helped matters. It also reveals that a more active rewrite might be an improvement: "Thinking too much is your problem."

Now, let's rashly perform reconstructive surgery on a much more complex sentence:

"It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife."

First, let's spoil it by inverting it:

"That a single man in possession of a good fortune must be in want of a wife is a truth universally acknowledged."

Now, just to see what happens, let's lop of the "that":

"A single man in possession of a good fortune must be in want of a wife is a truth universally acknowledged."

... Oh dear, what have we done.

In conclusion: Sometimes the "that" helps make the syntax clear. Sometimes a reorganization of the syntax is even better.