There is quite a bit of difference between changing out of an engineering major because the student discovered something else that is more interesting, versus being forced out because his/her 3.2 GPA led to being “weeded out” of an oversubscribed engineering major. In the latter case, it may be a rather bad situation to be involuntarily forced out of the major, when one still has interest in it and could have successfully graduated in it at some other school.
Those who change out of engineering out of interest discover their plan B during college (i.e. finding some other major that interests them more). Those who face an aggressive “weeding” process need to consider a different kind of plan B (e.g. transfer to another school) to complete their major if they are “weeded out” despite doing reasonably well in it and still having interest in it.
Note that aggressive “weeding” is not necessarily limited to engineering majors. Some liberal arts majors at some schools are oversubscribed, so they need to “weed out” prospective majors to stay within capacity.