Invisibility still has no Counter-play
Exactly what the title says, despite changes occurring twice a month now (one major, one minor) Riot's Gameplay design team has consistently avoided introducing counter-play to invisibility. Now before I get comments saying but you can see Twitch/Rengar/Evelynn if they get too close, let me explain that Invisibility is listed in one of two categories by Riot.
The first is Camouflage which is the mechanic used by Eve/Rengar/Twitch, Camouflaged champions are revealed by control/pink wards along with being seen if they get to close. Think along the lines of Military Reconnaissance and Ghilie Suits, if you ever get too close to one of these groups then it's very likely you'll spot them.
The second type of Invisibility is what I'd call "True Invisibility." This is the idea that: despite your proximity to said champion/person they are completely hidden from you. Think of them as being an intangible entity, you can only briefly see where they are, but there's not much you can do to fight back against them.
Now the key difference between the two types of Invisibility is that one has a means to counter-play against, while the other poses no counter-play whatsoever outside of actually hitting them with spells. Prior to the invisibility mechanic getting changed, invisibility had a fair amount of counter-play and utility for people playing with and against the mechanic. If people didn't invest in a pink ward when playing against a champion with invisibility then the deaths that would occur due to their oversight would be their own fault, the people who did buy pink wards to counter invisibility were putting gold into an item that could have been better used for vision control rather than fighting an invisibility champion, the amount of gold put into pink wards would set players builds back by about 100g every time they had to purchase a pink ward.
The justification for changing the way invisibility worked was: It doesn't feel good to have a single mechanic of your kit be countered by a 75g item.
That was the quote the Balance Team, lead by Meddler, gave when they changed the way Invisibility worked. Meddler's team had changed a long standing mechanic that everyone was OK with for an obscure reason without providing enough detail as to why it had to be done the way they have it now as compared to other ways they could have changed the Invisibility Mechanic.
Side Note: More than likely one of two things will happen to this post.
The first being someone downvotes the post without actually reading through it because they disagree with my opinions.
The second is even if this post does gain traction on the Boards a Rioter from the Balance Team wouldn't reply because it questions their design process and the choices that they are making. Rioter's dislike it when hard questions are asked and tend to avoid those with the excuse of "I didn't work on it so I don't know much." Changes to the game are archived and readily accessible to Riot Employee's if they need to reference them, this would also include the thought process behind them.