The first thing I would do is make a distinction between the role of Business Analyst and the skill of Business Analysis. This may seem like an unimportant distinction now, but it will pay off long-term.
In Scrum, and in SAFe, there is an expectation that teams are engaged in uncovering and identifying the requirements. This absolutely requires the skill of business analysis and if the teams don't have that, it'll be challenging, as they've already identified. Here is where making that distinction will change actions though. There is only one way to add the role: hire/assign the person. However, there are many ways to add the skill. You can add a person with that skill, but you can also try to identify if people on some of the teams already have that skill. Perhaps one or two of your developers have BA experience and expertise. You can have a senior BA or two mentor the teams to help them learn to ask the right questions.
On complex projects, the teams are absolutely right that they need that skillset, but if they are looking for someone else to take on that responsibility so they don't have to, that can be very problematic for many reasons. To name a few:
1) the team still needs to understand the context, so that BA needs to re-explain everything after they understand it - information the team could have gotten first hand.
2) it creates a success bottleneck where the whole process hinges on one person (adds fragility to your process)
3) ever play whisper-down-the-alley in school? You're doing that with your BA with a complex project
4) it may (emphasis on may) be them setting up a fall guy if the project fails.
So, in conclusion, I'd help the team address the need for the business analysis skill but I would be very hesitant to solve that problem with a person who entirely owns that skill.