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The development of alignment within Roleplaying Games is an interesting topic. Fantasy RPG's tend to have rules and setting information covering it, while other genres tend to gloss over it or focus on other sources of conflict.
In this post, I'll focus on Dungeons & Dragons, partly because it's what I'm most familiar with, but also because the evolution over time within D&D tends to be quite closely mirrored by other fantasy systems.
The Development of Alignment in Dungeons & Dragons
I'm not going to go into a detailed history here, others have done that in a far better way than I could ever aspire to.
Suffice to say that alignment started as a very simple law/chaos/neutral split where good and evil were inherently built in rather than considered separately. It was a simpler time, and we were all murder-hobos back then....
Over the first few editions (AD&D, 2nd Edition, 3.0, 3.5 etc), alignment evolved becoming more detailed and prescriptive, going to a 4-way split, then a 9-way one. D&D 3.5 is where alignment reached it's peak, with plenty of spells and magic items that really leaned into the whole alignment system. My personal favourite (which I still use to this day) is a 17-way split that was never actually official but has lots of wonderful nuance to it.
In 4th Edition, Wizards of the Coast tried something different, re-imposing a more limited and controlled structure. I've not played it, but if you accept that 4th Edition was intended to be like an MMORG played on the tabletop, it seems to fit the brief well.
Now we are on 5th Edition, WOTC seem to have gone with the zeitgeist of the times, giving a quick nod to alignment in the Players Handbook, but stripping out most of the mechanical workings. It is clear they are uncomfortable with the idea of alignment, because it inevitably involves some stereotyping by species as well as the idea that there are clearly opposed forces in the universe.
The Problems With Structured Alignment
The process of creating more structure around alignment up to D&D 3.5 increased role-playing opportunities, but at the expense of a lot more complications and even disagreements both IC and OOC as players and DM's wrestled with the interpretations of what alignments actually meant and how strictly they should be played.
An example of the problems this can cause are a paladin in a game I ran recently. The player interpreted the alignment so strictly that he'd do a Detect Evil on pretty much everyone the party met. He would either attack or refuse to deal with the ones who came up positive, depending on whether he thought he could beat them. This even happened when a key quest-giver (and reward giver !) showed up as mildly evil. The consequences of this down the line could well affect the overall story arc, making failure much more likely and success much harder work !
Pushing players into defined alignment roles works for some groups and some players, but can cause significant issues if there is too great a divergence of interpretation and approach within a group. In my opinion, it gives too much of an excuse for the players who go down the "it's what my character would do" route.
The Problems With Minimal Alignment Rules
With WOTC's recent moves to sideline alignment amid concerns about diversity and discrimination, I worry that D&D will lose a bit part of the heroic flavour which goes with having a cosmic struggle between implacably opposed belief systems.
Without alignment, clerics become just another flavour of magic user and paladins are just a sub-class of fighter. Characters without the moral compass of alignment risk being nothing more than murderous treasure-hunters, and it becomes a lot harder for GM's to write adventures without the conflict between good and evil or law and chaos as over-arching themes. Heavily aligned monsters such as demons and celestials kind of lose their purpose, becoming just a stat block.
A game world with no alignment would tend to edge towards being a gritty place where there is no particular incentive to show mercy, and the only sanction against those who do wrong is if those they have wronged are strong enough to oppose them.
Conclusion
I'm guilty of both of these extreme approaches to alignment at different times. But I do believe that alignment is an important facet of fantasy RPG's, even though it can be handled in a variety of ways.
I am starting to work towards a solution which works for my homebrew world, even if nowhere else.... I'll go into more detail in my next post, this one has turned into a long enough ramble !