Shiny initial textAreaInput value and reactive after each button press

Description

I have a textAreaInput box that I want to start with a default value. The user can click 2 actionButtons (Submit & Random Comment). Submit updates the comment from the textAreaInput for further processing (plot, etc.) while Random Comment sends a new random value to textAreaInput (the user may type in the textAreaInput box as well). I almost have it but can't get the app to update textAreaInput's value until the Submit button is pressed.

Question

I want it to be updated when Random Comment is pressed but still allow the user to erase the text box and type their own text. How can I make the app do this?

MWE

library(shiny)
library(shinyjs)
library(stringi)

shinyApp(
    ui = fluidPage(
      column(2,
        uiOutput("randcomment"),
        br(),
        div(
            actionButton("randtext", "Random Comment", icon = icon("quote-right")),
            div(actionButton("submit", "Submit", icon = icon("refresh")), style="float:right")
        )

      ),
      column(4, div(verbatimTextOutput("commenttext"), style = 'margin-top: 2cm;'))
    ),
    server = function(input, output) {

        output$randcomment <- renderUI({
            commentUi()
        })

        comment_value <- reactiveValues(default = 0)

        observeEvent(input$submit,{
            comment_value$default <- input$randtext
        })

        renderText(input$randtext)

        commentUi <- reactive({

            if (comment_value$default == 0) {
                com <- stri_rand_lipsum(1)
            } else {
                com <- stri_rand_lipsum(1)
            }

            textAreaInput("comment", label = h3("Enter Course Comment"), 
                value = com, height = '300px', width = '300px')
        })

        output$commenttext <- renderText({ input$comment })


    }
  )