my feeling personally is that battletech is more akin to chess, in that the rules are fairly simple but the interactions and choices made during a game are or can be very complex.
The problem with this analogy is that while Battletech is more complicated than other wargames in the same way that Chess is more complicated than Checkers, a lot of Battletech's complexity comes solely from pages upon pages of numbers and charts and not anything inherent to the game itself. Assuming legal moves, your Knight will always capture my Pawn, 100% of time. No dice rolling, no modifiers, no box of death, no extra dice on the table to remind you how many spaces you moved or whether I used jump jets. It just happens. That is nowhere near the case with Battletech.
As other have said, Battletech, at the basic level, is actually a really simple game. At the core, it is just adding up a bunch of numbers, rolling some dice, and consulting some charts. But every single thing in the game has its own chart and its own roll and its own drawn out resolution process. And some actions require rolling against multiple different charts multiple times.
Then you add the 3050 tech, and the list of weapons - and their associated stats - goes from a dozen to two full pages, most of which are duplicates of each other and only slightly different because of a very halfhearted attempt at faction flavor.
Then you add some advanced rules, and suddenly you need to check the terrain table for movement costs because you stepped onto a Level 3 mud hex and you need to roll a couple of dice to determine whether or not your Locust skids across the map because you took a corner too quickly which requires ANOTHER lookup table.
The fact that Battletech tries to be a more granular wargame in a sea of very abstract systems is an admirable goal. It adds something to the market that simply doesn't exist elsewhere. The fact that that granularity comes at a painfully slow pace absolutely kills my enthusiasm for digging out my minis, though. I simply don't have the time to invest simple 4v4 game when I know that most of that time is going to be spent counting hexes and checking To-Hit tables.
THAT BEING SAID... one thing that I feel compelled to point out in these threads is that exactly nobody posting to this discussion has any idea of what does, or does not move product for CGL. Yes, most (all?) of the best selling games on the market right now use much faster systems than Battletech, but if CGL thinks it can derive a profit from pushing the exact same rules with the exact same slow-burn resolution
and attract new players to the game, that's what they should do. CGL doesn't make Battletech for me. They make it because they believe that it can turn a profit.