Yes. For most SaaS/Web Apps the pre-login site is a sales site, not the actual product. (see basecamp, salesforce, kissmetrics etc.,) and you may be spending too much time before you launch the landing page, preventing you from getting feedback quickly from your MVP/Dry-run.
In a second phase, you can go back and do it from scratch, when you have more time and resources.
Over at WPEngine we're finding a lot of people are using us to host their Saas/Web App landing/sales/info site in WordPress and then run their app at app.domain.com via AWS, Heroku, etc.
Wordpress allows you to decouple the "info site" stack from the web app stack, which are not necessarily the same technologies - and so this can go way beyond just MVP.
In a second phase, you can go back and do it from scratch, when you have more time and resources.