Adversarial Question: Why not fork LND Loop and provide the service freely/cheaply? Adversarial Question: Now that LND Loop is paid product, what stops someone from forking the software and selling the product themselves, or integrating it freely?

The only reason I can think of is that Loop is still maturing as a product, and that it is LND who will bring  it to maturity, so it makes sense to stay with the proprietors. But that's not even relevant when the service becomes mature.
LND Loop is an open-source solution with MIT Licence. So, you are free to fork the code and create your own solution without any restrictions. In fact, there are a number of submarine swap companies out there that offer you a solution to import/export liquidity from your channel. LND Loop will just be one amongst a sea of such solutions. Market share winners and losers would be differentiated from their customer service and how they are going to tailor the solution to the customer needs.

A classic example to consider is Docker. Its code is completely open source (Apache 2.0 license) for Linux distributions and you can fork it if you want. However, Docker has raised $307.9M in funding to date and has a valuation in billions. They make money through their enterprise editions, docker hub and other professional services.

In my opinion, a similar analogy can be drawn for lightning. In the future, the company that will be able to handle huge requests of loop-ins and loop-outs without sacrificing time will grab a majority market share. They will have to tailor their solution to their customers and provide the best service possible. This will require considering multiple factors including good backend technology to handle the load, good professional services and if the company is able to handle enterprise implementations for their Lightning payment needs. They will also need to figure out liquidity and fluctuations in market price of Bitcoin to handle such operations. Offering all the services at a low cost is what is going to differentiate the competition. Forking off the code is just the first small step.