It should be obvious from pretty much the first time it happens that in missions where you engage multiple lances your first priority is to split them and to engage them one at a time. This is literally the most important tactical principle in the whole game. Everything else is secondary. If you have 5+ enemies - especially enemies on screen and not guys firing LRMs from outside sensor range - activating after you've finished your turn you are doing it wrong, there's really no way around saying that.
Sure you can take multiple head hits in a single mission, but your mechwarriors advance to 4 health very quickly, so even taking multiple head hits should not result in death. As for melee attacks, this rarely occurs unless you're deliberately inviting it. Anything you get into melee range should die before it gets a chance to counter, and the AI rarely goes for melee attacks unless out of weapons.
I was being fairly obviously hyperbolic. Yes occasional misses on high-percentage shots happen, particularly with autocannons due to some wonky-ness with physical obstacles, but they are unlikely. You should never depend on any single weapon to hit, and certainly not to kill (since even if it hits the called shot percentage never goes above 90%).As for "A full 10 Mechwarrior never misses", hit chance never exceeds 95%. I had one miss two such shots in a row; in the next to last mission, I had 2 targets that each only needed a tap to finish because I had split my force to secure multiple objectives, so the Mech that had LoS to both fired a laser at each of them and missed both. Which was irritating because the only Mech that hadn't acted was my missile boat and I had to dedicate an entire LRM20 to each of them or let them inflict a bunch more damage to my team.
Overall I do not think my experience is atypical. I reloaded a number of times in my first playthrough - to mitigate mech damage not pilot loss - but this was necessary mostly because I hadn't figured out bulwark properly and it took some time to learn to optimize my Precise Shot and Vigilance usage. Even then, it was mostly a mitigation measure, I could have used withdrawal if I'd wanted, but I was forcing myself to beat even extremely difficult enemy loadouts.
As Drasius said 'easy game is easy.' This is not an especially hard tactical combat game. It's much less punishing than X-COM and allows nearly infinite grinding. It's not that cakewalk that say, MechCommander 2 was, but it's not especially hard.
Bigger mechs mean more armor, more damage, and more specialties and pretty much always have. It is the rare moment in any game in the Battletech universe where you don't want to field the most hulking monstrosity available, something that's been true at least as far back as MechWarrior 2 (which deliberately limited your tonnage as its primary difficulty measure). This is especially true in the tactical environment. The advantage of a faster unit is that it can get to places where the enemy is not, or has insufficient resources, but this is a strategic rather than tactical advantage and this game is largely devoid of strategic elements. Also, the map simply isn't big enough to make movement speed a major factor in any mission, and I don't know if you can change that without severe alterations to the engine.Overall, fun game, good Battletech, but it isn't great that it is a one way trip towards heavier mechs. There should be some kind of pressure pushing tonnage down, either in the missions (fast enemies who try and escape) or strategy layer (maybe heavier mechs take more than one bay? Or a mandatory refurb time even without damage, so you have to cycle more mechs?) Those are my modding targets once the patches settle down.