I'm gonna play devil's advocate here, because while I do agree with most of your points (I like the slightly longer games that are more even as well) I feel like you do not necessarily speak for the majority of the playerbase, and that you probably have not considered the complexities of your statements in context of the overall game. I don't have answers, I'm just asking these questions to get thought going on what actually is involved (at least, to my mind) in some of these changes.
So first off, do "we" want longer games? You might be the average voice of NA, but what does Korea have to say about the matter? What tier of play are we talking about? Why 30 minutes and not 33? Is there really a "best" average game length for maximum enjoyment? I think it's fairly clear that there's a lot of personal opinion regarding this question.
I recall reading somewhere recently that the average game length was something like 27 or 28 minutes. Is that close enough to 30? How systematic do you need to be to bump the game time up, and will that make an actual difference?
Towers going down, average dragons, baron - those are purely balance issues with that particular mechanic, so adjusting then should be easy if it were decided that doing so was necessary. Personally, I think dragons are currently fine and turrets too weak.
Mid laner gold at X time. This is a crazy one. Anivia and Talon get their gold in almost entirely different ways, yet both are mid laners. How do you determine if kill gold needs to be higher (more snowballing - helpful to roaming mids) or minion gold needs to be higher (helpful to farming mids) to reach this goal? What will adjusting either do to the other lanes and jungle? Do mages need better farming/last hitting options (more CS compared to now) to reach that gold goal? What will this do to items that are bought/mid lane power spikes?
I'm going to assume here that average mid lane CS is roughly equal to average top/bot CS at the end of lane phase - if mid lane is getting the same farm, but feels like they're down on gold compared to side lanes, what does that mean? Fewer kills/assists? Less chance of pushing towers down? Where is the difference coming from? You can't hope to solve a "problem" if you don't know whats causing it. Are mage items just too expensive? If you make mage items cheaper, what will that do to bot lane with the mage supports like Brand, etc?
And how do you balance gold difference between teams in a reasonable manner? If one team has great objective control and the other team doesn't, shouldn't that reflect in team gold? I get that you want to be able to leverage a winning fight into a comeback, but how do you ensure the gap isn't too large on average? More gold for shutdowns? Less gold from baron/dragon/turrets? Playing with these mechanics seems risky to me (though I am a fan of putting all towers back to 150 global gold). How do you reward players for doing the "right" thing in game - or offer strategic options that are "equally good" - without providing them too much benefit? If the dragon is always worth 150 gold (in pure gold, or effects) and towers are worth 175 gold, shouldn't taking a tower ALWAYS be the better option?
But even then, say we get the game to be as you would like - a bit longer, a bit slower, maybe even a bit more even between teams. How do you then balance champions around it? Going back to my previous post, how do you decide that Ziggs is doing too well at getting towers early, and what do you do about it? Is it Ziggs' fault that roaming mid laners are popular, so he is picked to pressure mid? Is that not a valid counter strategy? Does enforcing one state of game balance remove options that would otherwise be valid if there was no enforcement? In other words, if Ziggs is nerfed because he's taking tower too fast, doesn't that defeat the point of picking Ziggs against a roaming mid - all because it was decided that turrets, on average, shouldn't go down before 12 minutes? Doesn't that give an unfair advantage to the roaming mids?
The big question on the state of the game's balance is, to my mind, "Is the current environment of the game one that every champion can equally succeed in?" Or, to put it another way, "Are there champions that are unsuccessful in the current state of the game?" Now, you can define unsuccessful in any manner of ways, but overall - to me, personally - it feels like I have the opportunity to be successful with any champion I choose for a game. Isn't that a good indication of balance on a champion level, and therefore indicates the game, from at least one point of view, is technically balanced? You may not agree with its balanced state (as I noted, we agree that game pacing could be better) but I never look at champ select and say "Oh, I want to play X and I can't because I will for sure lose with them." And yes, that used to be the case back in season 3 and 4. Eve, Urgot, Kalista - there were a handful of champions that were actually bad across the board, regardless of play, team support, etc.