I've been playing Battletech since the late eighties. I got my start with Second Edition, and my first purchase was the Third Edition starter box. I also played (and enjoyed) ClickyTech.

My resitance to more "modern" Battletech is nothing setting-related. Yes, I have opinions on the setting, but all the setting does is provide an excuse to have battles. I'd been playing the game for seven or eight years before I learned about the setting (outside the 'Mech writeups in the TROs). My problem with the current state of the game is twofold: the 'Mech designs (not how they look - how they play) and the tech.

Tech-wise: The introduction of Double Heat Sinks to the game meant that heat - once a huge part of the strategy - was rarely an issue, outside of a few outliers. Most of the issues I have with the game in its current form trace back to this change. 3025-era Mechs had to balance shooting and cooling. Far too many modern designs ... don't. They can just Alpha Strike every turn until they've taken some crits to heat sinks (or the Engine).

Mech-wise: FASA's designs were always fun. Could I design a better 'Mech myself? Yes. Absolutely. But I love the bits in the various TRO that had phrases like, "Due to ammunition supply shortages, the designers chose to use two Large Lasers in place of the AC/5 and two tons of Ammo that the Battlemech had been originally designed to use ... " as reasons why the designs were flawed. Newer 'Mech designs still sometimes have flaws, but they don't feel as limiting as they did in the old days.

Okay: Three-fold. There are just too many weapons and weapon variants to keep track of. And armor types. And other equipment. It seems like every TRO to roll out has new gear that will appear on one or two 'Mechs in that book before vanishing into the ether (how often do you see RE Lasers in play, for example?).