Sure, there can be in abstract. However, what happens in practice is a lot more situational, and dependant on a series of additional factors that are on top of the model itself, but that we must keep into consideration.
For example, monopolization is bad news for users, regardless of the model - both can be more or less monopolistic. However, the current paradigm is relatively dispersed as far as game production and publishing goes, because users disperse their expenses on a game-by-game basis, so the system allows for several independent publishers, and even self-published games, to exist. If you move towards a subscription based model in line with what Microsoft is planning, the user is put in front of a drastically reduced number of options on where to practically spend the money. There could exist a "softer" subscription-based model in theory, where individual publishers create mini-subscriptions for all of their products, but it's quite obvious that is not what we are looking at right now.
This centralization inevitably deals a blow to healthy competition, because now individual users cannot "punish" individual game makers for bad products or practices, they are forced to accept the whole package as it is, good and bad, because there is a new agent in the system that acts as a blurring screen between people paying and studios delivering the goods. And since this entity in the middle has agency of its own, and can direct or even dictate to game makers, there are even more chances of anti-consumer practices being pushed on the users via syndication.
If we assume that your premise (total expenditure per user goes up), there are only two ways it can happen: either you up quality of games (and their budget) leading people to willingly dedicate more of their income into the hobby, or the extra money comes from the economic package being offered masking the real cost to the average user and leading them to spend more over time out of unawareness/apathy/habit.
What is preventing the first option to also happen right now, with the current model? It does happen already in fact, because certain platforms have overall attach rates higher than others, and it's usually those platform with a larger and better catalogue to offer. So, is this really an advantage of a subscription system, or just an external factor for which the model is irrelevant?
And in light of this, my next question is: if the subscription system by its very nature succeeds in increasing the per-user expenditure over a certain period of time... where is the incentive to re-invest the extra money into making better games exactly?
Is the door really more open though? It's a bit of a risky statement, because in this scenario the door for anything is exactly as open or close as Microsoft (or whoever manages the service) wants it to be, no more, no less. You assume Microsoft might want to go there. Remember that you moved from a mostly open market where by law of large numbers untapped demand will eventually receive offer, to one where a very limited amount of central entities hold unprecedented control over what is published and what isn't. Sure, in theory the same could be said for console makers right now as well, but remember that you are also moving towards a model where the effective "success" of any game goes through an opaque glass panel and it becomes a lot harder to outline failure and success regardless of what a platform holder could decide to promote right now.
But even if we completely disregard all of these specific considerations, my reasoning on why I don't want to see this is incredibly straightforward.
The gaming industry is a very simple market once you strip it down to the basics: products come from one single side, game publishers, and money comes from one single source, consumers. The goal of publishers is to end up with the highest possible amount of money, subtracting all they spent for game development and adding what users paid them for the products. The goal of consumers is to end up with the best possible product offering according to their standards for as cheap as possible. If the system moves too far in one of the two directions (which can happen on a company-by-company basis or on a wider level) either the customers stop playing games or the studios can't pay the bills anymore (and either one also leads in turns to the other).
This is an inescapable truth of the system, and a service-based model won't change that. Games will still come from a single direction, and money will still come from the other one. If the service will be too terrible people will stop paying, and if the offer will be too good for the customers studios will start closing down. You are shuffling the intermediate steps a bit, but neither of the two fundamental sides of the equations have changed.
Now, considering all this, ask yourself: since what is changing is the shape of the road, but neither the beginning or the end of the journey, why do you think Microsoft would want to pay billions to push for this change? Every last penny they spent to ensure games coming to Game Pass, or entire studios becoming dedicated to making games for it, is a penny they plan to recoup from you later down the line. And it's not money spent strictly speaking in game development, it's not you giving a company twice as much for a product that is twice as good, the games could have been developed even without all of this other money on top of it just to alter the product delivery method. If making Assassin's Creed 19 costs 100, why would Microsoft throwing Ubisoft an additional 20 just to guarantee the game comes to Game pass?
Microsoft is investing hard in a restructuring of the gaming economical system; and where do you think the point of balance of the new system they planned and paid for will lie? Will it be one where the user has it better than now, or where Microsoft does?
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