I see many posts and comments disparaging the riven system in Warframe, definitely moreso than praise for, so I figured I would throw my two cents into the void.
The overall sentiment against rivens existing is based on the fact that the rolls/weapon/type are random, that they are expensive to obtain good or "god" rolls (in both platinum and kuva), and that they are subject to decreased stats in the event of a disposition nerf to said weapon. I can see that all of these points are very valid, however my take on the riven experience has been quite different.
I enjoy that they offer an (extremely) long term goal to get certain rolls on rivens you have and to obtain rivens for specific weapons you want. Personally, I never buy good rolls unless the price is low like the weapon is unpopular. For many, I get them with intent to reroll until I happen to get lucky, and I usually have at least three that I am in the process of rolling.
Another point is that the rivens themselves are not needed at all, fun to have, but not needed. Therefore it is literally no detriment to ignore the system completely.
In regards to the disposition of certain weapons decreasing, and therefore making rivens less useable, correct me if I'm wrong, but disposition can go back up as well, it is not a permanent thing, and the riven has the same "stats." In my eyes, it just makes me want those really good rolls more.
Another thing rivens allow are fun and wacky builds like the negative projectile speed stug, or even making less powerful weapons worth giving a shake. I now like the Glaxion vandal quite a bit after scoring an amazing riven for cheap, and it shreds steel path now!
On the dark side of rivens, people are generally pretty greedy with prices for good rivens, however this has the upside that if you unveil a decent riven, or roll it a few times, for a weapon that you don't care about, you can get a decent chunk of plat usually. Using riven.market or warframe market to sell means you just wait for buyers and don't even have to deal with trade chat.
Speaking of trade chat, rivens offer an infinitely many sources of commerce, as there are always new rivens being unveiled, always rolls you might want, and occasionally new weapons or mods/upgrades making old weapons relevant again, it adds to the finite amount of items like frames, weapons, and standard mods that can be traded.
To sum everything up, I enjoy the riven system quite a bit for many reasons, maybe it is because I am used to games with the grind for the .001% item and enjoy the chase. The feeling when you do roll a riven and get the three good positive and one harmless negative or the actual "Groll," makes all the kuva and time worth it to me. I am interested to hear people's thoughts on the Riven system in general but more interestingly, people's thoughts on my reasons for enjoying the system.
TLDR, Rivens are fun to me, rolling them, selling them, grinding kuva. I think the system is good for the longevity of trading, and does a good job of enabling wacky builds and making less viable into viable. I also don't mind disposition nerfs as good rolls are still worth slotting, and disposition can go back up.
Thank you for reading.
That's just my calling card.