At the moment, we have no plans to add information about the dataset of the selected item to our events.

You can do this easily using the returned value in the event:

<select id="select" data-mdb-select-init>
  <option data-var="var1" value="1">One</option>
  <option data-var="var2" value="2">Two</option>
  <option data-var="var3" value="3">Three</option>
  <option data-var="var4" value="4">Four</option>
</select>

const selectEl = document.querySelector('#select')
selectEl.addEventListener('optionSelected.mdb.select', (e) => {
  const selectedOptionEl = selectEl.querySelector(`option[value="${e.value}"]`)
  console.log(selectedOptionEl.dataset.var)
})

Hi, It is very important for me that we need to access also data attributes. It shouldn't be that difficult to pass data attributes, don't you think?

The optionSelected event return only value of the selected option.