This code can really be improve, I know, that's juste a first try.
This field type provide à media explorer alone, without wysiwyg. This is quite a replacement for 'image' field.
1 Button "add image" to show Magento 2 admin media explorer.
1 Button "delete image" for non required field (like checkbox on file / image field)
Nothing required, just put this file anywhere on one of your module, and then use it as type of field :
$fieldset->addField(
'myimage',
'Mynamespace\Mymodule\Block\Adminhtml\Mediastorage\Helper\Mediastorage',
[
'name' => 'myimage',
'label' => __('Image with super media explorer'),
'title' => __('Image with super media explorer'),
]
);