The wifi splash page and redirection is a holdover of days gone past and something I have never understood the need for. Companies want to use it for promotional or monetary purposes that would seem to have nothing to do with giving the guest a better experience at the property. I can tell you as a managed services provider of wifi that most calls coming into our support center have to do with issues related to the splash page and the guest getting online.
Using the splash page for promotional purposes I think is dubious. So we are going to redirect the guest after login to the web page of the hotel they are already booked at? Might be some use to promote amenities at large full service properties but I see no benefit at midscale and below.
Using the splash page for monetization such as redirecting to a page full of ads seems like risking guest experience for very little reward. Over the past 20 years I have seen many monetization schemes for wifi and they all went out of business.
Using a splash page also makes it difficult for a guest with devices that have no bowser to get online. Devices such as game machines, AppleTVs, Rokus, Fire Sticks, etc have to be manually authenticated requiring guest to make a call to support.
I see no benefit for the guest so I say get rid of it!