Type cast TimeSpan to DateTime relative to now (Get-Date)

TimeSpan to DateTime

Currently the following statement produces an error:

[DateTime](New-TimeSpan -Days 7)

InvalidArgument: Cannot convert the "7.00:00:00" value of type "System.TimeSpan" to type "System.DateTime".

The idea is that it would make more sense if it would actually cast to a DateTime type relative to now (Get-Date).
(Get-Date).Add(<TimeSpan>), e.g.: (Get-Date).Add((New-TimeSpan -Days 7)):

Example 1

[DateTime](New-TimeSpan -Days 7)        # As of Sunday, December 27, 2020 10:13:18 AM
Sunday, January 3, 2021 10:13:18 AM     # Wishful thinking

Example 2

$After = New-TimeSpan -Days -14
$Before = New-TimeSpan -Days -7
Get-EventLog -LogName System -EntryType Error -After $After -Before $Before

Example 3

function Get-WeekDay ([DateTime]$Date) {
    "{0:d MMMM yyyy} is a {0:dddd}." -f $Date
}

Get-WeekDay 'January 1, 2021'
1 January 2021 is a Friday.

Get-WeekDay (New-TimeSpan -Days 5)      # Instead of: Get-WeekDay (Get-Date).Add((New-TimeSpan -Days 5))
1 January 2021 is a Friday.             # Wishful thinking

Related

#14496 New OlderThan and NewerThan parameters for Get-ChildItem cmdlet

The added suggestion You might also consider to accept (besides a DateTime type) a TimeSpan type: will simply be impliciet:

$30DaysAgo = New-TimeSpan -Days -30
Get-ChildItem $Path -Recurse -OlderThan $30DaysAgo

#12305 A simple method for creating TimeSpan objects to enable more user-friendly and simple usage of time-dependent Cmdlets

And together with this purpose it might even get to
(where -OlderThan is just a parameter of [DateTime] type as orginally purposed):

Get-ChildItem $Path -Recurse -OlderThan -30Days

No implementation files, tests, or entry points are named. Start by reviewing the PowerShell conversion behavior and related issues #14496 and #12305; done would be a decided and tested rule for converting a TimeSpan to a DateTime relative to Get-Date, including the examples shown.