SOAPUI versus HP UFT versus Powershell for SOAP/REST API testing have all their own pros and cons.
Powershell is powerfull with one line of code you import your wsdl and directly you have the power at your fingertips. So far not anything seen thats more quicker and nice part its on everyone's windows machines including servers.
For HP UFT you have to know the context menu to send away simple xml's in 1-2 seconds otherwise you are compiling which quickly gives you 2-3 minutes delay. The nice flowchart you get as a present from HP UFT for your documentation. Developers probably do not like the VBScripting stuff which is rather outdated language but with power of dotnetfactory object you can also deal from VBScript with .NET namespaces.
(New-Object System.Net.WebClient).Proxy.Credentials = [System.Net.CredentialCache]::DefaultNetworkCredentials
$url = "http://www.webservicex.net/globalweather.asmx?wsdl"
$webservicex = New-WebServiceProxy -Uri $url -namespace WebServiceProxy -Class GlobalWeatherSoap
$webservicex | gm
SOAPUI is very intuitive when you start it but for the more complex things you have to use Groovy scripting.