Why did Harvey and Jessica deceive Mike about their ploy regarding Monica and Hardman? After all, Mike's on their side. Well, remember, they know Mike's not quite tough thanks to the mock trial, but they need him to be - so him acting out of his idealism and loyalty is more useful than trying to get him to be dishonest. Also, Louis seeing Mike is integral to the ploy - any sign of falsehood, Louis might see. Lastly, they're also trying to protect Mike - his part ends up looking like a mere pawn rather than a valuable player; if their ploy failed, Hardman would be less likely to hurt Mike as much comparatively. Hardman might even try to use Mike later if he thought Mike was still useful in some way.
Harvey's and Mike's tragic success is heartbreaking, yes. But you know how Jessica has noted that Harvey is similar to Hardman and that Mike is similar to Harvey? On a broader scale then, their tragedies are suppose to be similar to Hardman's - doing something else rather than spending time with family. In Hardman's case, however, rather than getting caught up in work, he gets caught up in panties.
In the first season, Mike has to practically drag Harvey into a fist bump. Now, they gleefully play HORSE in the office together. It's not because Harvey has become less of a stickler for such things, but rather, he's now more comfortable with Mike and more willing to open up and seem vulnerable (or mortal, at any rate).