this is what happens to you when you see mechanics that make sense
first you are impressed by adding 1-2 points in skills… you are becoming so much stronger
then you are impressed by blue magic items that you randomly find
then you realize that there are synergies and that you may optimize your skills, you are beginning to understand builds
then you finish normal
then you are having a bit of trouble and you start finding more usefull items, gems, runes
you realize that there are sockets and runewords
there are items that give skill bonuses
you realize that you need to build you resistances
you start planning
you go for obedience, pride and other items
you start reading, you learn about fcr, crushing blow, prefixes and sufixes
you finish nightmare
you start getting problems with immunities so you are starting to consider alternative damage types, even better builds. Gear and runewords are now a necessity
you realize that you can farm certain areas
you realize the value of MF and that there are sets and class specific items
you realize that you can kill the DClone and get the best small charm
you farm a lot, you optimize for fire and lightning res, you are in search of skillers
you win the game in p1 and start farming in p8
you realize that there is a grail quest, outside the game
you start understanding the value of some rare drops
you realize that there is the world event
you start considering the possibility to go for lvl 99
you have tried a couple of sorcs, necros, amazons and pallys who have been good enough to finish the game but strive above lvl90 or so… you are starting to consider finer optimizations
you realize that you can play with friends
you realize that you can speedrun
you realize that you can go hardcore
you realize that you can play online (which is another game)
you realize that you can trade
you realize that you can pvp (which is another world entirely)
you are having a great time and maybe a lot of time has passed. All these mechanics work and are meaningful. You have read the formulas, understood them, and they make sense. You start comparing the eras of the game. Were the era before runewords better? Did enigma run the game? Is pride OP for its money ? Should the melee chars be stronger ? Are the casters OP in comparison ? Should all skills be viable in the endgame ? Are some new runewords OP and break the game ? How much of a problem are the bots ? Is the economy of the game rational ?
as the time has passed you realize that D2/D2R is the best game you have ever played (and you have played quite a few) and you do not want it to end up like other game. You would like to see it thrive and you would certainly pay for an expansion or new content
this is not exhaustive, written quickly
the point is that all of the above is a progressive learning experience that keeps in interested and focused… it is so very rare…
you have read a lot, you now know the history of the game and you comprehend that all of this can be easily ruined if the game diverges from its roots… you play D3, you play D4 and you understand that this is what they are missing… so you do not want D2/D2R to lose its unique character, its unique soul that makes it an absolute stand out among the graphically well polished current ARPG…
is this enough for you ?