I see this question as a long running, yet very subtle and stealthy problem--meaning, it's one most people don't see as a problem and thus don't say anything. "Convenience items" from cash shops exist for one reason: because the game is designed to inconvenience you for no other reason than to sell that convenience piecemeal. This creates a game where the majority of content is designed with time sinking in mind just to rope you into losing patience and spending more money to skip content. These games also tend to sell themselves on their "endgame," with the other 90% of the game simultaneously being the best part and the most disposable. Extra Credits recently taught me a new term for such disposable gameplay: accretion.
In my opinion, paying to skip parts of a game you've paid for is absolute lunacy. Regardless of whether it's something you could or couldn't get in game, paying MORE to get LESS game hours is like paying double ticket price to get into a movie that's already 60 minutes in. BUUUUUUT if a game is purposely designed to bloat itself on the "boring parts," then speeding things up for a few bucks makes perfect sense, right? See the insidiousness of the problem here?
I think if a game isn't designed to sell convenience by purposely being inconvenient, then it's freed up to sell the cool things instead of things the we "need" in order to "catch up." Even if those items aren't literal power boosts, they're often things that accelerate your pace of progress so fast that you miss parts of the game intended to teach you things or share a memorable experience with you.
Even something as innocuous-looking as bigger inventory space for a few bucks can DRASTICALLY increase the pace of your progress, completely eliminating huge chunks of time wherein you must "go back to town." I'd much rather have a game where "going back to town" isn't a dull and tedious afterthought, but instead of designed to be interesting and engaging in itself, thankyouvermuch.
The short answer to this question, "how much convenience should/will there be?" is thus: "Only enough convenience to help mitigate the unintentionally, yet unavoidably tedious aspects of an otherwise well-thought out and engaging experience!"
Which is what I think Grummz is aiming for.
