Based on the photos, it appears that the tooth is missing a lot of healthy tooth structure. You can try to restore the tooth with a root canal/buildup/crown. However, because there is limited tooth structure remaining it can make the tooth more susceptible to fracturing in the future. An implant, although a little longer of a treatment option, will give you a better long term outcome. It also saves you the time and cost of trying to restore the tooth and ultimately still needing an implant in the future.
Without a picture, x-ray, or clinical exam it is hard to make that determination. Most likely the dentist is recommending a crown/veneer because the bonding has been replaced a few times and is continuing to chip. A crown/veneer may not be needed however. There could be an interference with current bite which is causing the bonding to chip. Usually the bonding itself chips and not the tooth itself. When a bonding is re-done however, if not done correctly more of your natural tooth may be removed each time the bonding is replaced. A crown/veneer is a stronger, longer lasting option compared to a bonding and is usually needed when limited tooth structure is remaining.
Your story is one of the most common dental stories we hear. The aesthetics of your crown will vary from dentist to dentist. The reason for that is the dental laboratory used to fabricate that crown. Not all dental labs are the same just like not all restaurants are the same even if they offer similar menus. The bulkiness and the color of the crown tell me that the crown was most likely not fabricated by a master ceramist (a dental technician who has immense experience in recreating nature with their dental restorations). A single dental crown on the upper front teeth is also one of the hardest dental procedures for most dentists. Not because of the actual dentistry, but due to the difficulty in matching a single crown to your surrounding natural teeth. In dentistry we always want to be taking symmetry into consideration as well. Once your aligners are completed and you are happy with how the teeth appear it would most likely be best to have the crown re-done if you are still unhappy with the aesthetics and even consider a veneer on the adjacent front tooth. This would help more evenly match the front 2 teeth and add more symmetry.
What is aesthetically acceptable can vary from person to person. What should not vary is the function/adaptation of the dental restoration to the tooth. From the x-ray it is hard to tell, but does appear that the crown is fully seated and has acceptable marginal adaptation (meaning the crown fits the tooth and there are no visible areas of openings between the crown and the tooth). The aesthetics can vary based on the dental laboratory used and the quality of the restoration. It is too hard to say without a clinical examination if crown lengthening was needed or not. Irregardless of the crown lengthening, the crown can be designed to close small spaces between the teeth/gums which allows for proper at-home hygiene which along with function should be what determines if a restoration is acceptable or not.
It is possible to reshape the veneers. From the photos I can see, the veneers do not follow your natural contour of your lips and smile. Usually we need to remove the old dentistry and place correctly fabricated restorations that follow your facial aesthetics. More importantly we need restorations that allow for proper biologic form and function. You mention you had a anterior open bite. Sometimes this can be corrected with veneers, however, based on the photos there may be something a little more going on with the bite/function. This can lead to not only possible problems with the muscles and joints later in life, but can lead to uneven pressure/stress on the teeth. The veneers as you stated looked "squared off and jokerish". This is because of the design and porcelain ceramic used. To look more natural and life-like, we need to have the veneers designed and finished by a master ceramist.
